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/da.json

@@ -12,6 +12,7 @@
   "Logout": "Log ud",
   "Login": "Log ind",
   "Providers": "Udbydere",
+  "Style": "Stil",
   "Usage": "Forbrugsstatistik",
   "API Key": "API-nøgle",
   "Connected": "Forbundet",
@@ -176,6 +177,7 @@
   "How it works:": "Sådan virker det:",
   "Antigravity/Copilot IDE request → DNS redirect to localhost:443 → MITM proxy intercepts → 9Router → response to Antigravity/Copilot": "Antigravity/Copilot IDE-anmodning → DNS-omdirigering til localhost:443 → MITM-proxy aflytter → 9Router → svar til Antigravity/Copilot",
   "No API keys — create one in Keys page": "Ingen API-nøgler — opret en på Keys-siden",
+  "e.g. a warm, gentle voice, speaking slowly with a British accent": "fx.: en varm, blød stemme, der taler langsomt med britisk accent",
   "sk_9router (default)": "sk_9router (standard)",
   "Server started": "Server startet",
   "Failed to start server": "Fejl ved start af server",