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

test-keycloak-mobile.ps1

@@ -0,0 +1,70 @@
+# Test de la configuration Keycloak pour mobile
+$KeycloakUrl = "http://192.168.1.11:8180"
+$Realm = "unionflow"
+$ClientId = "unionflow-mobile"
+
+Write-Host "=== TEST CONFIGURATION KEYCLOAK MOBILE ===" -ForegroundColor Cyan
+Write-Host ""
+
+# 1. Test du realm
+Write-Host "1. Test du realm '$Realm'..." -ForegroundColor Yellow
+try {
+    $realmConfig = Invoke-RestMethod -Uri "$KeycloakUrl/realms/$Realm/.well-known/openid_configuration"
+    Write-Host "   ✅ Realm accessible" -ForegroundColor Green
+    Write-Host "   Authorization endpoint: $($realmConfig.authorization_endpoint)" -ForegroundColor Gray
+    Write-Host "   Token endpoint: $($realmConfig.token_endpoint)" -ForegroundColor Gray
+} catch {
+    Write-Host "   ❌ Realm non accessible: $($_.Exception.Message)" -ForegroundColor Red
+    exit 1
+}
+
+# 2. Test du client mobile
+Write-Host "2. Test du client '$ClientId'..." -ForegroundColor Yellow
+try {
+    # Obtenir token admin
+    $tokenBody = "username=admin&password=admin&grant_type=password&client_id=admin-cli"
+    $tokenResponse = Invoke-RestMethod -Uri "$KeycloakUrl/realms/master/protocol/openid-connect/token" -Method Post -ContentType "application/x-www-form-urlencoded" -Body $tokenBody
+    $accessToken = $tokenResponse.access_token
+    
+    # Vérifier le client
+    $headers = @{ "Authorization" = "Bearer $accessToken" }
+    $clients = Invoke-RestMethod -Uri "$KeycloakUrl/admin/realms/$Realm/clients?clientId=$ClientId" -Method Get -Headers $headers
+    
+    if ($clients.Count -gt 0) {
+        $client = $clients[0]
+        Write-Host "   ✅ Client trouvé" -ForegroundColor Green
+        Write-Host "   Enabled: $($client.enabled)" -ForegroundColor Gray
+        Write-Host "   Public Client: $($client.publicClient)" -ForegroundColor Gray
+        Write-Host "   Standard Flow: $($client.standardFlowEnabled)" -ForegroundColor Gray
+        Write-Host "   Redirect URIs: $($client.redirectUris -join ', ')" -ForegroundColor Gray
+        
+        # Vérifier les redirect URIs
+        $expectedUri = "com.unionflow.mobile://login-callback/*"
+        if ($client.redirectUris -contains $expectedUri) {
+            Write-Host "   ✅ Redirect URI correct" -ForegroundColor Green
+        } else {
+            Write-Host "   ⚠️ Redirect URI manquant: $expectedUri" -ForegroundColor Yellow
+        }
+    } else {
+        Write-Host "   ❌ Client non trouvé" -ForegroundColor Red
+    }
+} catch {
+    Write-Host "   ❌ Erreur: $($_.Exception.Message)" -ForegroundColor Red
+}
+
+# 3. Test d'authentification utilisateur
+Write-Host "3. Test d'authentification utilisateur..." -ForegroundColor Yellow
+try {
+    $userBody = "username=test@unionflow.dev&password=test123&grant_type=password&client_id=$ClientId"
+    $userResponse = Invoke-RestMethod -Uri "$KeycloakUrl/realms/$Realm/protocol/openid-connect/token" -Method Post -ContentType "application/x-www-form-urlencoded" -Body $userBody
+    
+    Write-Host "   ✅ Authentification réussie" -ForegroundColor Green
+    Write-Host "   Access token reçu: $($userResponse.access_token.Substring(0, 50))..." -ForegroundColor Gray
+    Write-Host "   Token type: $($userResponse.token_type)" -ForegroundColor Gray
+    Write-Host "   Expires in: $($userResponse.expires_in) secondes" -ForegroundColor Gray
+} catch {
+    Write-Host "   ❌ Échec authentification: $($_.Exception.Message)" -ForegroundColor Red
+}
+
+Write-Host ""
+Write-Host "=== DIAGNOSTIC TERMINÉ ===" -ForegroundColor Cyan