fix(mobile): support QR scanning without Play Services

packages/mobile/HANDOFF.md

@@ -81,9 +81,10 @@ iOS Simulator helpers: `mobile:sim:{boot,install,launch,run,serve,list,kill}` (s
 - **Connection onboarding** — server URL entry, password unlock for locked servers, client-token
   issuance, saved connections, `Instances` management sheet, auto-connect to the last instance on
   launch. Deleting the active instance resets the runtime to the connect screen.
-- **QR pairing** — `@capacitor-mlkit/barcode-scanning`. Android's Google code scanner module is
-  downloaded on first scan (needs Play Services + network); `mobileQrScan.ts` installs/awaits it
-  and retries. CAMERA permission + `NSCameraUsageDescription` declared.
+- **QR pairing** — `@capacitor-mlkit/barcode-scanning`. Android uses the CameraX-backed
+  `startScan()` flow with the barcode model bundled in the app, so scanning works offline and
+  without Google Play Services. iOS uses the plugin's native scanner. CAMERA permission +
+  `NSCameraUsageDescription` declared.
 - **Secure storage** — `@aparajita/capacitor-secure-storage` for connection tokens.
 - **Deep links** — `openchamber://` URL scheme; a reusable intent vocabulary (`apps/deepLinks.ts`)
   used by notification taps, widgets, and Control Center. Cold-launch intents are stashed.
@@ -128,8 +129,7 @@ iOS Simulator helpers: `mobile:sim:{boot,install,launch,run,serve,list,kill}` (s
   brings `firebase-messaging`.
 - Manifest: permissions `INTERNET`, `CAMERA` (+ optional camera feature), `POST_NOTIFICATIONS`
   (Android 13+; older versions allow notifications by default). `windowSoftInputMode=adjustResize`.
-  ML Kit `com.google.mlkit.vision.DEPENDENCIES=barcode_ui` meta (preloads the code scanner). FCM
-  `default_notification_icon=@drawable/ic_stat_notify`.
+  FCM `default_notification_icon=@drawable/ic_stat_notify`.
 - Adaptive launcher icon: full-bleed color background + `ic_launcher_foreground` (sources under
   `packages/mobile/assets/`, regenerable with `@capacitor/assets`).