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/hi.json

@@ -12,6 +12,7 @@
   "Logout": "लॉग आउट",
   "Login": "लॉगिन",
   "Providers": "प्रदाता",
+  "Style": "शैली",
   "Usage": "उपयोग के आंकड़े",
   "API Key": "API कुंजी",
   "Connected": "जुड़ा हुआ",
@@ -176,6 +177,7 @@
   "How it works:": "यह कैसे काम करता है:",
   "Antigravity/Copilot IDE request → DNS redirect to localhost:443 → MITM proxy intercepts → 9Router → response to Antigravity/Copilot": "Antigravity/Copilot IDE अनुरोध → DNS को localhost:443 में पुनर्निर्देशित करें → MITM प्रॉक्सी इंटरसेप्ट करता है → 9Router → Antigravity/Copilot को प्रतिक्रिया",
   "No API keys — create one in Keys page": "कोई API कुंजी नहीं — Keys पृष्ठ में एक बनाएं",
+  "e.g. a warm, gentle voice, speaking slowly with a British accent": "जैसे: गर्म, कोमल आवाज़, ब्रिटिश लहजे में धीरे-धीरे बोलते हुए",
   "sk_9router (default)": "sk_9router (डिफ़ॉल्ट)",
   "Server started": "सर्वर शुरू किया गया",
   "Failed to start server": "सर्वर शुरू करने में विफल",