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/HomePage.qml

@@ -22,7 +22,7 @@ Rectangle {
 
     // ===== View State =====
     property int selectedTabIndex: 0
-    property int selectedSideActionIndex: 0
+    property int selectedSideActionIndex: -1   // nothing active on startup
 
     // ===== Main Two-Column Layout =====
     RowLayout {
@@ -57,7 +57,13 @@ Rectangle {
                         Layout.fillWidth: true
                         Layout.preferredHeight: Math.max(Theme.sideButtonMinHeight, sideRail.computedButtonHeight)
                         hoverEnabled: true
-                        onClicked: root.selectedSideActionIndex = index
+                        onClicked: {
+                            root.selectedSideActionIndex = index
+                            root.selectedTabIndex = 0          // always jump to Status tab
+                            if (index === 0) deviceController.detectWafer()
+                            else if (index === 1) deviceController.readMemoryAsync()
+                            else if (index === 2) deviceController.openCsvFile()
+                        }
 
                         background: Rectangle {
                             color: {
@@ -138,9 +144,21 @@ Rectangle {
                                     source: parent.tabName === "Settings" ? "Tabs/SettingsTab.qml" : ""
                                 }
 
+                                Loader {
+                                    anchors.fill: parent
+                                    active: parent.tabName === "Status"
+                                    source: parent.tabName === "Status" ? "Tabs/StatusTab.qml" : ""
+                                }
+
+                                Loader {
+                                    anchors.fill: parent
+                                    active: parent.tabName === "Data"
+                                    source: parent.tabName === "Data" ? "Tabs/DataTab.qml" : ""
+                                }
+
                                 Label {
                                     anchors.centerIn: parent
-                                    visible: parent.tabName !== "Settings"
+                                    visible: parent.tabName !== "Settings" && parent.tabName !== "Status" && parent.tabName !== "Data"
                                     text: parent.tabName + " content"
                                     color: Theme.bodyColor
                                     font.pixelSize: 20