Add comprehensive automated testing infrastructure

Backend:
  - pytest configuration with async support and coverage
  - Unit tests for notification service (23 tests)
  - Unit tests for smart plug manager (12 tests)
  - Unit tests for archive service (16 tests)
  - Integration tests for API endpoints
  - Fix: notifications now send immediately (digest is summary only)

  Frontend:
  - Vitest configuration with jsdom and coverage
  - MSW for API mocking
  - Component tests for Toggle, Button, Card, ConfirmModal (77 tests)
  - Test utilities with custom render wrapper

  CI/CD:
  - GitHub Actions workflow for automated testing
  - Backend lint, unit tests, integration tests
  - Frontend lint, type-check, unit tests, build

backend/tests/integration/test_printers_api.py

@@ -0,0 +1,284 @@
+"""Integration tests for Printers API endpoints.
+
+Tests the full request/response cycle for /api/v1/printers/ endpoints.
+"""
+
+import pytest
+from httpx import AsyncClient
+from unittest.mock import patch, MagicMock, AsyncMock
+
+
+class TestPrintersAPI:
+    """Integration tests for /api/v1/printers/ endpoints."""
+
+    # ========================================================================
+    # List endpoints
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_list_printers_empty(self, async_client: AsyncClient):
+        """Verify empty list is returned when no printers exist."""
+        response = await async_client.get("/api/v1/printers/")
+
+        assert response.status_code == 200
+        assert response.json() == []
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_list_printers_with_data(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify list returns existing printers."""
+        printer = await printer_factory(name="Test Printer")
+
+        response = await async_client.get("/api/v1/printers/")
+
+        assert response.status_code == 200
+        data = response.json()
+        assert len(data) >= 1
+        assert any(p["name"] == "Test Printer" for p in data)
+
+    # ========================================================================
+    # Create endpoints
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_create_printer(self, async_client: AsyncClient):
+        """Verify printer can be created."""
+        data = {
+            "name": "New Printer",
+            "serial_number": "00M09A111111111",
+            "ip_address": "192.168.1.100",
+            "access_code": "12345678",
+            "is_active": True,
+            "model": "X1C",
+        }
+
+        response = await async_client.post("/api/v1/printers/", json=data)
+
+        assert response.status_code == 200
+        result = response.json()
+        assert result["name"] == "New Printer"
+        assert result["serial_number"] == "00M09A111111111"
+        assert result["model"] == "X1C"
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_create_printer_duplicate_serial(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify duplicate serial number is rejected."""
+        await printer_factory(serial_number="00M09A222222222")
+
+        data = {
+            "name": "Duplicate Printer",
+            "serial_number": "00M09A222222222",
+            "ip_address": "192.168.1.101",
+            "access_code": "12345678",
+        }
+
+        response = await async_client.post("/api/v1/printers/", json=data)
+
+        # Should fail due to duplicate serial
+        assert response.status_code in [400, 409, 422, 500]
+
+    # ========================================================================
+    # Get single endpoint
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_get_printer(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify single printer can be retrieved."""
+        printer = await printer_factory(name="Get Test Printer")
+
+        response = await async_client.get(f"/api/v1/printers/{printer.id}")
+
+        assert response.status_code == 200
+        result = response.json()
+        assert result["id"] == printer.id
+        assert result["name"] == "Get Test Printer"
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_get_printer_not_found(self, async_client: AsyncClient):
+        """Verify 404 for non-existent printer."""
+        response = await async_client.get("/api/v1/printers/9999")
+
+        assert response.status_code == 404
+
+    # ========================================================================
+    # Update endpoints
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_update_printer_name(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify printer name can be updated."""
+        printer = await printer_factory(name="Original Name")
+
+        response = await async_client.patch(
+            f"/api/v1/printers/{printer.id}",
+            json={"name": "Updated Name"}
+        )
+
+        assert response.status_code == 200
+        assert response.json()["name"] == "Updated Name"
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_update_printer_active_status(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify printer active status can be updated."""
+        printer = await printer_factory(is_active=True)
+
+        response = await async_client.patch(
+            f"/api/v1/printers/{printer.id}",
+            json={"is_active": False}
+        )
+
+        assert response.status_code == 200
+        assert response.json()["is_active"] is False
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_update_printer_auto_archive(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify auto_archive setting can be updated."""
+        printer = await printer_factory(auto_archive=True)
+
+        response = await async_client.patch(
+            f"/api/v1/printers/{printer.id}",
+            json={"auto_archive": False}
+        )
+
+        assert response.status_code == 200
+        assert response.json()["auto_archive"] is False
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_update_nonexistent_printer(self, async_client: AsyncClient):
+        """Verify updating non-existent printer returns 404."""
+        response = await async_client.patch(
+            "/api/v1/printers/9999",
+            json={"name": "New Name"}
+        )
+
+        assert response.status_code == 404
+
+    # ========================================================================
+    # Delete endpoints
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_delete_printer(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify printer can be deleted."""
+        printer = await printer_factory()
+        printer_id = printer.id
+
+        response = await async_client.delete(f"/api/v1/printers/{printer_id}")
+
+        assert response.status_code == 200
+
+        # Verify deleted
+        response = await async_client.get(f"/api/v1/printers/{printer_id}")
+        assert response.status_code == 404
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_delete_nonexistent_printer(self, async_client: AsyncClient):
+        """Verify deleting non-existent printer returns 404."""
+        response = await async_client.delete("/api/v1/printers/9999")
+
+        assert response.status_code == 404
+
+    # ========================================================================
+    # Status endpoint
+    # ========================================================================
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_get_printer_status(
+        self, async_client: AsyncClient, printer_factory, mock_printer_manager, db_session
+    ):
+        """Verify printer status can be retrieved."""
+        printer = await printer_factory()
+
+        response = await async_client.get(f"/api/v1/printers/{printer.id}/status")
+
+        assert response.status_code == 200
+        result = response.json()
+        assert "connected" in result
+        assert "state" in result
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_get_printer_status_not_found(self, async_client: AsyncClient):
+        """Verify 404 for status of non-existent printer."""
+        response = await async_client.get("/api/v1/printers/9999/status")
+
+        assert response.status_code == 404
+
+    # ========================================================================
+    # Test connection endpoint
+    # ========================================================================
+
+class TestPrinterDataIntegrity:
+    """Tests for printer data integrity."""
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_printer_stores_all_fields(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """Verify printer stores all fields correctly."""
+        printer = await printer_factory(
+            name="Full Test Printer",
+            serial_number="00M09A444444444",
+            ip_address="192.168.1.150",
+            model="P1S",
+            is_active=True,
+            auto_archive=False,
+        )
+
+        response = await async_client.get(f"/api/v1/printers/{printer.id}")
+
+        assert response.status_code == 200
+        result = response.json()
+        assert result["name"] == "Full Test Printer"
+        assert result["serial_number"] == "00M09A444444444"
+        assert result["ip_address"] == "192.168.1.150"
+        assert result["model"] == "P1S"
+        assert result["is_active"] is True
+        assert result["auto_archive"] is False
+
+    @pytest.mark.asyncio
+    @pytest.mark.integration
+    async def test_printer_update_persists(
+        self, async_client: AsyncClient, printer_factory, db_session
+    ):
+        """CRITICAL: Verify printer updates persist."""
+        printer = await printer_factory(name="Original", is_active=True)
+
+        # Update
+        await async_client.patch(
+            f"/api/v1/printers/{printer.id}",
+            json={"name": "Updated", "is_active": False}
+        )
+
+        # Verify persistence
+        response = await async_client.get(f"/api/v1/printers/{printer.id}")
+        result = response.json()
+        assert result["name"] == "Updated"
+        assert result["is_active"] is False