Merge remote-tracking branch 'origin/master' into gitea/feature/end

Resolved conflicts taking origin/master (v0.5.55) as canonical, with local
features re-applied:
- runtime log level (LOG_LEVEL env + dashboard Settings → Logging, applied
  immediately and persisted across restarts)
- free/noAuth provider enable/disable toggle via providerStrategies.enabled
- parallel model testing (Test All Models / Test Selected Keys)

public/i18n/literals/fr.json

@@ -12,6 +12,7 @@
   "Logout": "Déconnexion",
   "Login": "Connexion",
   "Providers": "Fournisseurs",
+  "Style": "Style",
   "Usage": "Statistiques",
   "API Key": "Clé API",
   "Connected": "Connecté",
@@ -176,6 +177,7 @@
   "How it works:": "Comment ça marche :",
   "Antigravity/Copilot IDE request → DNS redirect to localhost:443 → MITM proxy intercepts → 9Router → response to Antigravity/Copilot": "Demande Antigravity/Copilot IDE → Redirection DNS vers localhost:443 → Le proxy MITM intercepte → 9Router → réponse à Antigravity/Copilot",
   "No API keys — create one in Keys page": "Aucune clé API — créez-en une dans la page Clés",
+  "e.g. a warm, gentle voice, speaking slowly with a British accent": "ex. : voix chaleureuse et douce, parlant lentement avec un accent britannique",
   "sk_9router (default)": "sk_9router (par défaut)",
   "Server started": "Serveur démarré",
   "Failed to start server": "Impossible de démarrer le serveur",