feat(obico): AI print-failure detection via self-hosted Obico ML API (#172)

Adds a Failure Detection tab under Settings that wires Bambuddy to a
  self-hosted Obico ml_api container — no cloud, no account, no WebSocket.
  While a print is running, the detection service periodically hands the
  printer's camera snapshot URL to the ML API and smooths scores over
  time (30-frame warmup + EWM, alpha=2/13, short/long rolling means) so
  one noisy frame can't trigger an action. When the smoothed score
  crosses HIGH, the configured action fires exactly once per print:
  notify, pause, or pause-and-cut-power (via linked smart plugs).

  - Backend: new obico_detection + obico_smoothing + obico_actions
    services, /obico/status and /obico/test-connection routes
    (SETTINGS_READ / SETTINGS_UPDATE), six obico_* AppSettings fields
    with validators for sensitivity/action/enabled_printers.
  - Frontend: FailureDetectionSettings component (enable, ML URL + test,
    sensitivity, action, poll interval, per-printer monitor list, live
    status + detection history), new sidebar tab with service-active
    bullet, toast on save.
  - Tests: 17 detection unit tests + 15 smoothing unit tests + 4
    frontend component tests.
  - Docs: README bullet, CHANGELOG entry, wiki page under Analytics,
    website features.html entry.

backend/app/api/routes/obico.py

@@ -0,0 +1,48 @@
+"""API routes for Obico AI failure detection."""
+
+import logging
+
+from fastapi import APIRouter
+from pydantic import BaseModel
+
+from backend.app.core.auth import RequirePermissionIfAuthEnabled
+from backend.app.core.permissions import Permission
+from backend.app.models.user import User
+from backend.app.services.obico_detection import obico_detection_service
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/obico", tags=["obico"])
+
+
+class TestConnectionRequest(BaseModel):
+    url: str
+
+
+@router.get("/status")
+async def get_status(
+    _: User | None = RequirePermissionIfAuthEnabled(Permission.SETTINGS_READ),
+):
+    """Scheduler status, per-printer classification, and recent detection history."""
+    settings = await obico_detection_service._load_settings()
+    status = obico_detection_service.get_status()
+    return {
+        **status,
+        "enabled": settings["enabled"],
+        "ml_url": settings["ml_url"],
+        "sensitivity": settings["sensitivity"],
+        "action": settings["action"],
+        "poll_interval": settings["poll_interval"],
+        "external_url_configured": bool(settings["external_url"]),
+    }
+
+
+@router.post("/test-connection")
+async def test_connection(
+    req: TestConnectionRequest,
+    _: User | None = RequirePermissionIfAuthEnabled(Permission.SETTINGS_UPDATE),
+):
+    """Ping the Obico ML API `/hc/` health endpoint. Returns ok + raw body."""
+    if not req.url:
+        return {"ok": False, "status_code": None, "body": None, "error": "URL is empty"}
+    return await obico_detection_service.test_connection(req.url)