fix: context-aware .onion hint in API settings

When already on the .onion site, only show CORS reminder instead of
the confusing "Ensure you are using Tor Browser" message.

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

Author: Copexit

src/lib/api/url-diagnostics.ts

@@ -76,9 +76,13 @@ export function diagnoseUrl(url: string): UrlDiagnostic {
       "Your browser blocks HTTP requests from this HTTPS page. " +
       "Set up HTTPS on your node, or use SSH port forwarding to localhost.";
   } else if (result.isOnion) {
-    result.hint =
-      "Ensure you are using Tor Browser to reach .onion addresses. " +
-      "Your node also needs CORS headers for cross-origin requests.";
+    const pageIsOnion =
+      typeof window !== "undefined" &&
+      window.location.hostname.endsWith(".onion");
+    result.hint = pageIsOnion
+      ? "Your node needs CORS headers to allow cross-origin requests."
+      : "Ensure you are using Tor Browser to reach .onion addresses. " +
+        "Your node also needs CORS headers for cross-origin requests.";
   }
 
   return result;