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

create-mobile-client.ps1

@@ -0,0 +1,33 @@
+# Script simple pour créer le client mobile Keycloak
+
+Write-Host "Creation du client mobile Keycloak..." -ForegroundColor Cyan
+
+# Obtenir le token d'administration
+Write-Host "Obtention du token d'administration..." -ForegroundColor Yellow
+$tokenResponse = Invoke-RestMethod -Uri "http://localhost:8180/realms/master/protocol/openid-connect/token" -Method Post -Body "username=admin&password=admin&grant_type=password&client_id=admin-cli" -ContentType "application/x-www-form-urlencoded"
+$adminToken = $tokenResponse.access_token
+Write-Host "Token obtenu" -ForegroundColor Green
+
+# Créer le client mobile
+Write-Host "Creation du client mobile..." -ForegroundColor Yellow
+$headers = @{
+    Authorization = "Bearer $adminToken"
+    "Content-Type" = "application/json"
+}
+
+$clientJson = Get-Content "client-simple.json" -Raw
+
+try {
+    Invoke-RestMethod -Uri "http://localhost:8180/admin/realms/unionflow/clients" -Method Post -Headers $headers -Body $clientJson
+    Write-Host "Client mobile cree avec succes !" -ForegroundColor Green
+}
+catch {
+    if ($_.Exception.Response.StatusCode -eq 409) {
+        Write-Host "Client existe deja" -ForegroundColor Yellow
+    }
+    else {
+        Write-Host "Erreur: $($_.Exception.Message)" -ForegroundColor Red
+    }
+}
+
+Write-Host "Configuration terminee !" -ForegroundColor Green