fix(frontend/credentials): Handle stale credential IDs in CredentialsSelect

When a credential is deleted but the node still references its ID,
CredentialsSelect now treats the stale ID as unselected and falls
back to the first available credential instead of showing the raw ID.

autogpt_platform/frontend/src/components/contextual/CredentialsInput/components/CredentialsSelect/CredentialsSelect.tsx

@@ -42,11 +42,12 @@ export function CredentialsSelect({
     }
   }
 
+  // Resolve the selected credential — treat stale/deleted IDs as unselected
   const selectedCredential = selectedCredentials
     ? credentials.find((c) => c.id === selectedCredentials.id)
     : null;
 
-  // When credentials exist and nothing is explicitly selected,
+  // When credentials exist and nothing is matched,
   // default to the first credential instead of "None"
   const effectiveCredential =
     selectedCredential ?? (credentials.length > 0 ? credentials[0] : null);
@@ -73,21 +74,21 @@ export function CredentialsSelect({
           provider: provider,
         };
 
-  // Default to the first credential when any are available
+  // Use matched credential ID (not the raw selectedCredentials.id which may be stale)
   const defaultValue =
-    selectedCredentials?.id ??
+    effectiveCredential?.id ??
     (credentials.length > 0 ? credentials[0].id : "__none__");
 
   // Notify parent when defaulting to a credential so the value is captured on submit
   const hasNotifiedDefault = useRef(false);
   useEffect(() => {
     if (hasNotifiedDefault.current) return;
-    if (selectedCredentials?.id) return;
+    if (selectedCredential) return; // Already matched — no need to override
     if (credentials.length > 0) {
       hasNotifiedDefault.current = true;
       onSelectCredential(credentials[0].id);
     }
-  }, [credentials, selectedCredentials?.id, onSelectCredential]);
+  }, [credentials, selectedCredential, onSelectCredential]);
 
   return (
     <div className="mb-4 w-full">