feat: add Debrid-Link provider with multi-account key rotation

- New DebridLinkClient with automatic API key rotation on quota errors
  (maxLink, maxLinkHost, maxData, maxDataHost, maxAttempts, maxTransfer)
- Multi-account support: comma or newline-separated API keys
- Full UI integration: account settings, provider dropdowns, summary display
- Safe fallback for undefined debridLinkApiKeys on settings upgrade

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/constants.ts

@@ -52,6 +52,7 @@ export function defaultSettings(): AppSettings {
     ddownloadLogin: "",
     ddownloadPassword: "",
     oneFichierApiKey: "",
+    debridLinkApiKeys: "",
     archivePasswordList: "",
     rememberToken: true,
     providerPrimary: "realdebrid",