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-auth.ps1

@@ -0,0 +1,99 @@
+# Test Keycloak Authentication and API Call
+
+Write-Host "=== Test d'authentification Keycloak ===" -ForegroundColor Green
+
+# 1. Obtenir un token admin
+Write-Host "1. Obtention du token admin..." -ForegroundColor Yellow
+try {
+    $adminTokenResponse = Invoke-RestMethod -Uri "http://localhost:8180/realms/master/protocol/openid-connect/token" -Method Post -Body "username=admin&password=admin&grant_type=password&client_id=admin-cli" -ContentType "application/x-www-form-urlencoded"
+    $adminToken = $adminTokenResponse.access_token
+    Write-Host "✓ Token admin obtenu" -ForegroundColor Green
+} catch {
+    Write-Host "Erreur lors de l'obtention du token admin: $($_.Exception.Message)" -ForegroundColor Red
+    exit 1
+}
+
+# 2. Créer un utilisateur de test
+Write-Host "2. Création d'un utilisateur de test..." -ForegroundColor Yellow
+$testUser = @{
+    username = "testuser"
+    email = "test@unionflow.com"
+    firstName = "Test"
+    lastName = "User"
+    enabled = $true
+    credentials = @(
+        @{
+            type = "password"
+            value = "testpass"
+            temporary = $false
+        }
+    )
+} | ConvertTo-Json -Depth 3
+
+try {
+    $headers = @{
+        "Authorization" = "Bearer $adminToken"
+        "Content-Type" = "application/json"
+    }
+    
+    Invoke-RestMethod -Uri "http://localhost:8180/admin/realms/unionflow/users" -Method Post -Body $testUser -Headers $headers
+    Write-Host "✓ Utilisateur de test créé" -ForegroundColor Green
+} catch {
+    if ($_.Exception.Response.StatusCode -eq 409) {
+        Write-Host "✓ Utilisateur de test existe déjà" -ForegroundColor Green
+    } else {
+        Write-Host "Erreur lors de la creation de l'utilisateur: $($_.Exception.Message)" -ForegroundColor Red
+    }
+}
+
+# 3. Configurer le client unionflow-server pour permettre les direct access grants
+Write-Host "3. Configuration du client unionflow-server..." -ForegroundColor Yellow
+try {
+    # Obtenir l'ID du client
+    $clients = Invoke-RestMethod -Uri "http://localhost:8180/admin/realms/unionflow/clients?clientId=unionflow-server" -Headers $headers
+    if ($clients.Count -gt 0) {
+        $clientId = $clients[0].id
+        
+        # Mettre à jour le client pour permettre les direct access grants
+        $clientUpdate = @{
+            directAccessGrantsEnabled = $true
+            publicClient = $true
+        } | ConvertTo-Json
+        
+        Invoke-RestMethod -Uri "http://localhost:8180/admin/realms/unionflow/clients/$clientId" -Method Put -Body $clientUpdate -Headers $headers
+        Write-Host "✓ Client unionflow-server configuré" -ForegroundColor Green
+    }
+} catch {
+    Write-Host "Erreur lors de la configuration du client: $($_.Exception.Message)" -ForegroundColor Yellow
+}
+
+# 4. Obtenir un token utilisateur
+Write-Host "4. Obtention d'un token utilisateur..." -ForegroundColor Yellow
+try {
+    $userTokenResponse = Invoke-RestMethod -Uri "http://localhost:8180/realms/unionflow/protocol/openid-connect/token" -Method Post -Body "username=testuser&password=testpass&grant_type=password&client_id=unionflow-server" -ContentType "application/x-www-form-urlencoded"
+    $userToken = $userTokenResponse.access_token
+    Write-Host "✓ Token utilisateur obtenu" -ForegroundColor Green
+    Write-Host "Token: $($userToken.Substring(0, 50))..." -ForegroundColor Cyan
+} catch {
+    Write-Host "Erreur lors de l'obtention du token utilisateur: $($_.Exception.Message)" -ForegroundColor Red
+    Write-Host "Réponse: $($_.Exception.Response)" -ForegroundColor Red
+    exit 1
+}
+
+# 5. Tester l'appel API avec le token
+Write-Host "5. Test de l'appel API avec authentification..." -ForegroundColor Yellow
+try {
+    $apiHeaders = @{
+        "Authorization" = "Bearer $userToken"
+        "Content-Type" = "application/json"
+    }
+    
+    $apiResponse = Invoke-RestMethod -Uri "http://localhost:8080/api/evenements/publics" -Headers $apiHeaders
+    Write-Host "✓ Appel API réussi !" -ForegroundColor Green
+    Write-Host "Nombre d'événements: $($apiResponse.Count)" -ForegroundColor Cyan
+} catch {
+    Write-Host "Erreur lors de l'appel API: $($_.Exception.Message)" -ForegroundColor Red
+    Write-Host "Code de statut: $($_.Exception.Response.StatusCode)" -ForegroundColor Red
+}
+
+Write-Host "=== Test terminé ===" -ForegroundColor Green