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

keycloak_test_app/.metadata

@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "2663184aa79047d0a33a14a3b607954f8fdd8730"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: android
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: ios
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: linux
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: macos
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: web
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+    - platform: windows
+      create_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+      base_revision: 2663184aa79047d0a33a14a3b607954f8fdd8730
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'