feat(mobile): Implement Keycloak WebView authentication with HTTP callback

- Replace flutter_appauth with custom WebView implementation to resolve deep link issues
- Add KeycloakWebViewAuthService with integrated WebView for seamless authentication
- Configure Android manifest for HTTP cleartext traffic support
- Add network security config for development environment (192.168.1.11)
- Update Keycloak client to use HTTP callback endpoint (http://192.168.1.11:8080/auth/callback)
- Remove obsolete keycloak_auth_service.dart and temporary scripts
- Clean up dependencies and regenerate injection configuration
- Tested successfully on multiple Android devices (Xiaomi 2201116TG, SM A725F)

BREAKING CHANGE: Authentication flow now uses WebView instead of external browser
- Users will see Keycloak login page within the app instead of browser redirect
- Resolves ERR_CLEARTEXT_NOT_PERMITTED and deep link state management issues
- Maintains full OIDC compliance with PKCE flow and secure token storage

Technical improvements:
- WebView with custom navigation delegate for callback handling
- Automatic token extraction and user info parsing from JWT
- Proper error handling and user feedback
- Consistent authentication state management across app lifecycle

unionflow-server-impl-quarkus/pom.xml

@@ -77,10 +77,14 @@
             <artifactId>quarkus-flyway</artifactId>
         </dependency>
         
-        <!-- Sécurité JWT -->
+        <!-- Sécurité Keycloak OIDC -->
         <dependency>
             <groupId>io.quarkus</groupId>
-            <artifactId>quarkus-smallrye-jwt</artifactId>
+            <artifactId>quarkus-oidc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-keycloak-authorization</artifactId>
         </dependency>
         
         <!-- Configuration et santé -->
@@ -129,6 +133,11 @@
             <artifactId>rest-assured</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-test-security</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>