Fix virtual printer model codes and serial prefixes

- Correct SSDP model codes: C11=P1P, C12=P1S, N7=P2S, C13=X1E
  - Fix serial prefixes based on actual Bambu serial format
  - Add confirmation modal for pending upload discard
  - Sort model dropdown alphabetically, remove internal codes
  - Add "Setup Required" warning with link to wiki documentation
  - Update wiki with certificate installation and platform setup guides

backend/tests/unit/services/test_virtual_printer.py

@@ -126,7 +126,7 @@ class TestVirtualPrinterManager:
         assert status["running"] is True
         assert status["mode"] == "immediate"
         assert status["name"] == "Bambuddy"
-        assert status["serial"] == "00M09A391800001"
+        assert status["serial"] == "00M09A391800001"  # Constant X1C serial for cert stability
         assert status["model"] == "C11"
         assert status["model_name"] == "P1S"
         assert status["pending_files"] == 1