review: import before finishing on live scan; torch a11y default in layout

- Live scan now awaits importText() and then finish()es on the main thread, so
  importedN is populated before onDestroy() reads it (previously finished first,
  making the toast report '0 profile(s)').
- Layout torch FAB default contentDescription is now scan_torch_turn_on (matches the
  stateful runtime updates).

Author: hawkff

app/src/main/java/io/nekohasekai/sagernet/ui/ScannerActivity.kt

@@ -152,10 +152,13 @@ class ScannerActivity : ThemedActivity() {
             .addOnSuccessListener { barcodes ->
                 val text = barcodes.firstOrNull { !it.rawValue.isNullOrBlank() }?.rawValue
                 if (text != null && !finished.getAndSet(true)) {
-                    // First successful scan wins: finish the activity and import in the
-                    // background (the activity-scoped toast in onDestroy reports the count).
-                    finish()
-                    runOnDefaultDispatcher { importText(text) }
+                    // First successful scan wins. Import first, then finish on the main
+                    // thread, so importedN is populated before onDestroy() reads it for
+                    // the "N profile(s)" toast (finishing first raced the background import).
+                    runOnDefaultDispatcher {
+                        importText(text)
+                        onMainDispatcher { finish() }
+                    }
                 }
             }
             .addOnFailureListener { Logs.w(it) }

app/src/main/res/layout/layout_scanner.xml

@@ -40,7 +40,7 @@
         android:layout_height="wrap_content"
         android:layout_gravity="center_horizontal|bottom"
         android:layout_marginBottom="48dp"
-        android:contentDescription="@string/scan_toggle_torch"
+        android:contentDescription="@string/scan_torch_turn_on"
         android:src="@drawable/ic_baseline_flash_off_24"
         app:fabSize="normal" />