feat: add biometric authentication support and related UI screens

- Updated AndroidManifest.xml to include permissions for biometric authentication.
- Changed MainActivity to extend FlutterFragmentActivity for better compatibility.
- Modified gradle.properties to optimize memory settings.
- Enhanced app.dart to manage new app phases for biometric authentication.
- Implemented LocalVaultService methods for handling biometric key protection.
- Created BiometricChoiceScreen and BiometricGateScreen for user interaction.
- Updated HomeScreen to handle vault invalidation scenarios.
- Registered local_auth plugin for biometric functionality on macOS and Windows.
- Updated pubspec.yaml and pubspec.lock to include local_auth dependency.

android/app/src/main/AndroidManifest.xml

@@ -1,4 +1,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Permisos necesarios para autenticación biométrica en Android -->
+    <uses-permission android:name="android.permission.USE_BIOMETRIC" />
+    <uses-permission android:name="android.permission.USE_FINGERPRINT" />
     <application
         android:label="notas"
         android:name="${applicationName}"