feat(android): QR pairing — ZXing scanner + ScanPairingActivity + strings PT-PT

- Adiciona dependência zxing-android-embedded:4.3.0
- Adiciona permissão CAMERA e regista ScanPairingActivity no Manifest
- Cria ScanPairingActivity: scan QR → parse JSON → POST claim-device
- Adiciona preferência "Emparelhar dispositivo" nas definições do servidor
- Adiciona handler de clique em WhatSmsServerSettingsFragment
- Strings PT-PT: scan_qr_to_pair, pairing_success/failed/cancelled/error
- Bump versionName para 3.2.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/src/main/AndroidManifest.xml

@@ -7,6 +7,7 @@
         android:required="false" />
 
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+    <uses-permission android:name="android.permission.CAMERA" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_CONNECTED_DEVICE" />
@@ -84,6 +85,10 @@
             android:foregroundServiceType="dataSync"
             tools:node="merge" />
 
+        <activity
+            android:name=".ui.ScanPairingActivity"
+            android:exported="false" />
+
         <activity
             android:name=".MainActivity"
             android:exported="true">