fix: allow API Key editing in edit mode

Fixed logic in useApiKeyState.ts to correctly show API Key input
when editing existing providers. Changed condition from
`!isEditMode && hasApiKeyField(config)` to
`isEditMode && hasApiKeyField(config)` to match the original
form's behavior.

This restores the ability to directly update API keys when
editing existing providers that have API key fields in their
configuration.

src/components/providers/forms/hooks/useApiKeyState.ts

@@ -48,7 +48,7 @@ export function useApiKeyState({
   const showApiKey = useCallback(
     (config: string, isEditMode: boolean) => {
       return (
-        selectedPresetId !== null || (!isEditMode && hasApiKeyField(config))
+        selectedPresetId !== null || (isEditMode && hasApiKeyField(config))
       );
     },
     [selectedPresetId],