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/he.json

@@ -12,6 +12,7 @@
   "Logout": "התנתקות",
   "Login": "כניסה",
   "Providers": "ספקים",
+  "Style": "סגנון",
   "Usage": "סטטיסטיקה",
   "API Key": "מפתח API",
   "Connected": "מחובר",
@@ -176,6 +177,7 @@
   "How it works:": "איך זה עובד:",
   "Antigravity/Copilot IDE request → DNS redirect to localhost:443 → MITM proxy intercepts → 9Router → response to Antigravity/Copilot": "בקשת Antigravity/Copilot IDE → הפניה DNS ל-localhost:443 → פרוקסי MITM חוטף → 9Router → תגובה ל-Antigravity/Copilot",
   "No API keys — create one in Keys page": "אין מפתחות API — צור אחד בעמוד Keys",
+  "e.g. a warm, gentle voice, speaking slowly with a British accent": "למשל: קול חם ועדין, מדבר לאט במבטא בריטי",
   "sk_9router (default)": "sk_9router (ברירת מחדל)",
   "Server started": "השרת התחיל",
   "Failed to start server": "הפעלת השרת נכשלה",