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/data_model.py

@@ -0,0 +1,84 @@
+"""QAbstractTableModel for displaying parsed wafer temperature data in QML."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from PySide6.QtCore import QAbstractTableModel, Qt
+
+log = logging.getLogger(__name__)
+
+# Column roles for the temperature data table
+ROW_ROLE = Qt.ItemDataRole.UserRole + 1
+COL_ROLE = Qt.ItemDataRole.UserRole + 2
+
+
+class TemperatureTableModel(QAbstractTableModel):
+    """Table model for parsed wafer temperature data.
+
+    Exposes a 2D list of temperature strings to QML TableView.
+    Column 0 = row index, remaining columns = Sensor1, Sensor2, ...
+    """
+
+    def __init__(self, parent: Any = None) -> None:
+        super().__init__(parent)
+        self._data: list[list[str]] = []  # 2D array of temperature strings
+        self._col_count: int = 0  # Number of sensor columns (excludes row index)
+
+    def reset(self) -> None:
+        """Clear all data."""
+        self.beginResetModel()
+        self._data = []
+        self._col_count = 0
+        self.endResetModel()
+
+    def load_data(self, data: list[list[str]], col_count: int) -> None:
+        """Load parsed temperature data into the model.
+
+        Args:
+            data: 2D list of temperature strings (e.g. [["25.30", "24.80", ...], ...]).
+            col_count: Number of sensor columns (may differ from data[0] length).
+        """
+        self.beginResetModel()
+        self._data = data
+        self._col_count = col_count
+        self.endResetModel()
+        log.info("Loaded %d rows × %d cols into model", len(data), col_count)
+
+    # ---- QAbstractTableModel interface ----
+
+    def rowCount(self, parent: Any = None) -> int:
+        return len(self._data)
+
+    def columnCount(self, parent: Any = None) -> int:
+        # Column 0 = row index, columns 1..N = sensor values
+        return self._col_count + 1
+
+    def data(self, index: Any, role: int = ...) -> Any:
+        if not index.isValid():
+            return None
+
+        row = index.row()
+        col = index.column()
+
+        if role == Qt.ItemDataRole.DisplayRole:
+            if col == 0:
+                return str(row + 1)  # 1-based row index
+            sensor_col = col - 1
+            if row < len(self._data) and sensor_col < len(self._data[row]):
+                return self._data[row][sensor_col]
+            return "0"
+
+        return None
+
+    def headerData(
+        self, section: int, orientation: int, role: int = ...
+    ) -> Any:
+        if role != Qt.ItemDataRole.DisplayRole:
+            return None
+        if orientation == Qt.Orientation.Horizontal:
+            if section == 0:
+                return "Row"
+            return f"Sensor{section}"
+        return str(section + 1)