feat(ui): implement save directory browse button and pre-detection check

- Add a 'Browse...' button to the Connection Status panel in StatusTab.qml.
- Check if save directory is set before wafer detection in HomePage.qml, prompting the user if empty.
- Resolve QML Connections warning by renaming onLogMessageEmitted to onLogMessage.
- Remove temporary debug stack traces from device_controller.py.

src/pygui/ISC/HomePage.qml

@@ -2,6 +2,7 @@ import QtQuick
 import QtQuick.Controls
 import QtQuick.Layouts
 import ISC
+import QtQuick.Dialogs
 
 // ===== Home Workspace Shell =====
 Rectangle {
@@ -59,6 +60,26 @@ Rectangle {
        }
    }
 
+    function cleanFolderUrl(url) {
+        return decodeURIComponent(String(url).replace(/^file:\/\//, ""))
+    }
+
+    function _doDetect() {
+        root.memoryRead = false
+        streamController.setMode("review")
+        streamController.stopStream()
+        deviceController.detectWafer()
+    }
+
+    FolderDialog {
+        id: saveDirDialog
+        title: "Choose a folder to save Data"
+        onAccepted: {
+            deviceController.setSaveDataDir(root.cleanFolderUrl(selectedFolder))
+            root._doDetect()
+        }
+    }
+
     // ===== Main Two-Column Layout ======
     RowLayout {
         anchors.fill: parent
@@ -106,10 +127,11 @@ Rectangle {
                             root.selectedSideActionIndex = index
                             root.selectedTabIndex = 0          // always jump to Status tab
                             if (index === 0) {
-                                root.memoryRead = false
-                                streamController.setMode("review")
-                                streamController.stopStream()
-                                deviceController.detectWafer()
+                                if (!deviceController.saveDataDir) {
+                                    saveDirDialog.open()
+                                    return
+                                }
+                                root._doDetect()
                             }
                             else if (index === 1) {
                                 streamController.setMode("review")