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/build.gradle

@@ -13,7 +13,7 @@ android {
         minSdk 21
         targetSdk 33
         versionCode 11
-        versionName "3.1.0-hardcode"
+        versionName "3.2.0"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
 
@@ -130,6 +130,9 @@ dependencies {
     // Koin for Android
     implementation "io.insert-koin:koin-android:$koin_version"
 
+    // QR code scanner para emparelhamento WhatSMS
+    implementation 'com.journeyapps:zxing-android-embedded:4.3.0'
+
     testImplementation("junit:junit:4.13.2")
     androidTestImplementation("androidx.test.ext:junit:1.1.3")
     androidTestImplementation("androidx.test.espresso:espresso-core:3.4.0")