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

ISC/Tabs/StatusTab.qml

@@ -18,6 +18,11 @@ ColumnLayout {
     property alias waferCycles: waferCycles.text
     property bool waferDetected: false
 
+    // Latches true once any operation starts (or a previous session is
+    // restored) and never resets, so the status panel stays visible even
+    // when a detect finds no wafer.
+    property bool statusActive: false
+
     // Data summary after parse
     property int dataRows: 0
     property int dataCols: 0
@@ -28,14 +33,14 @@ ColumnLayout {
     Item {
         Layout.fillWidth: true
         Layout.fillHeight: true
-        visible: !root.waferDetected && !deviceController.operationInProgress
+        visible: !root.statusActive
     }
 
     // ===== Results area (shown once detect/operation runs) =====
     ColumnLayout {
         Layout.fillWidth: true
         Layout.fillHeight: true
-        visible: root.waferDetected || deviceController.operationInProgress
+        visible: root.statusActive
         spacing: Theme.rightPaneGap
 
         // --- Connection Status ---
@@ -217,7 +222,14 @@ ColumnLayout {
     // --- Signal Handlers ---
      Connections {
          target: deviceController
+         // Any operation start (detect/read/erase/debug) latches the panel on.
+         function onPortsUpdated() {
+             if (deviceController.operationInProgress)
+                 root.statusActive = true
+         }
+
          function onDetectResult(result) {
+             root.statusActive = true
              if (result && result.familyCode) {
                  root.waferDetected = true
                  waferInfoFamily.text = result.familyCode
@@ -233,6 +245,7 @@ ColumnLayout {
              // Show restored wafer info if available
              var info = deviceController.lastWaferInfo
              if (info && info.length > 0) {
+                 root.statusActive = true
                  root.waferDetected = true
                  waferInfoFamily.text = info[0] || "—"
                  waferSerial.text     = info[1] || "—"
@@ -242,6 +255,7 @@ ColumnLayout {
              }
              // Show data summary if data was previously parsed
              if (deviceController.dataRowCount > 0) {
+                 root.statusActive = true
                  root.dataParsed = true
                  root.dataRows = deviceController.dataRowCount
                  root.dataCols = deviceController.dataColCount