feat: Add OpenAI-compatible provider nodes

- Support multiple OpenAI-compatible providers with custom prefix/baseUrl
- Add provider nodes CRUD (create/read/update/delete)
- URL building: baseUrl + /chat/completions or /responses
- Model import from /models endpoint
- API key validation via /models
- Usage type safety across all translators
- OAuth token auto-refresh for expired tokens

src/app/api/translator/translate/route.js

@@ -91,7 +91,10 @@ export async function POST(request) {
         };
 
         // Build URL and headers
-        const url = buildProviderUrl(provider, model, true, { baseUrlIndex: 0 });
+        const url = buildProviderUrl(provider, model, true, {
+          baseUrlIndex: 0,
+          baseUrl: connection.providerSpecificData?.baseUrl
+        });
         const headers = buildProviderHeaders(provider, credentials, true, actualBody);
         
         result = {