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-server-client-simple.ps1

@@ -0,0 +1,40 @@
+# Script simple pour créer le client unionflow-server
+$KeycloakUrl = "http://192.168.1.11:8180"
+$Realm = "unionflow"
+
+Write-Host "Creation du client serveur..." -ForegroundColor Cyan
+
+# Obtenir le token
+$tokenBody = "username=admin&password=admin&grant_type=password&client_id=admin-cli"
+$tokenResponse = Invoke-RestMethod -Uri "$KeycloakUrl/realms/master/protocol/openid-connect/token" -Method Post -ContentType "application/x-www-form-urlencoded" -Body $tokenBody
+
+$accessToken = $tokenResponse.access_token
+Write-Host "Token obtenu" -ForegroundColor Green
+
+# Configuration du client
+$clientConfig = @{
+    clientId = "unionflow-server"
+    name = "UnionFlow Server API"
+    enabled = $true
+    clientAuthenticatorType = "client-secret"
+    secret = "unionflow-secret-2025"
+    publicClient = $false
+    standardFlowEnabled = $true
+    directAccessGrantsEnabled = $true
+    serviceAccountsEnabled = $true
+    redirectUris = @("http://192.168.1.11:8080/*")
+    webOrigins = @("http://192.168.1.11:8080")
+} | ConvertTo-Json
+
+$headers = @{
+    "Authorization" = "Bearer $accessToken"
+    "Content-Type" = "application/json"
+}
+
+try {
+    Invoke-RestMethod -Uri "$KeycloakUrl/admin/realms/$Realm/clients" -Method Post -Headers $headers -Body $clientConfig
+    Write-Host "Client serveur cree avec succes !" -ForegroundColor Green
+}
+catch {
+    Write-Host "Erreur: $($_.Exception.Message)" -ForegroundColor Red
+}