Add SettingsTab, StatusTab, DataTab and wire up DeviceController

- SettingsTab: chamber ID, master CSV mapping (families A-Z), wafer
  behavior toggle, light/dark mode toggle, Edit CSV Metadata dialog
- StatusTab: connection status card, wafer info, activity log (blank
  until Detect Wafer fires from the side rail)
- DataTab: empty state, ready for parsed data
- HomePage: side rail buttons dispatch device actions and jump to
  Status tab; selectedSideActionIndex defaults to -1 on startup
- DeviceController registered as QML context property in main.py
- LocalSettings: added status persistence fields
- Theme: added subheadingColor and disabledText
- Added serialcomm/ package and backend data/graph modules
- gitignore: restore clean version

backend/local_settings_model.py

@@ -48,14 +48,16 @@ class LocalSettingsModel(QObject):
         self._recompute_derived()
 
     def _resolve_data_dir(self) -> Path:
-        documents_dir = QStandardPaths.writableLocation(QStandardPaths.DocumentsLocation)
+        documents_dir = QStandardPaths.writableLocation(
+            QStandardPaths.DocumentsLocation
+        )
         base_dir = Path(documents_dir) if documents_dir else (Path.home() / "Documents")
         return base_dir / "isc_data"
 
     def _new_defaults(self) -> dict[str, Any]:
         return {
             "chamberId": "2",
-            "reverseZWafer": True,
+            "reverseZWafer": False,
             "debugMode": False,
             "waferReadTimeout": 120000,
             "waferDetectTimeout": 5000,
@@ -250,7 +252,9 @@ class LocalSettingsModel(QObject):
     @Slot()
     def loadSettings(self) -> None:
         loaded = LocalSettings.read_settings(str(self._data_dir))
-        self._chamber_id = str(loaded.chamber_id).strip() or str(self._defaults["chamberId"])
+        self._chamber_id = str(loaded.chamber_id).strip() or str(
+            self._defaults["chamberId"]
+        )
         self._reverse_z_wafer = bool(loaded.reverse_z_wafer)
         self._debug_mode = bool(loaded.debug)
         self._wafer_read_timeout = int(loaded.wafer_read_timeout)