fix: Model Manager scan Auto Add not detecting checkpoint correctly (#3810)

## What type of PR is this? (check all applicable)

- [ ] Refactor
- [ ] Feature
- [ ] Bug Fix
- [ ] Optimization
- [ ] Documentation Update


## Have you discussed this change with the InvokeAI team?
- [ ] Yes
- [ ] No, because:

      
## Description


## Related Tickets & Documents

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- Related Issue #
- Closes #

## QA Instructions, Screenshots, Recordings

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## Added/updated tests?

- [ ] Yes
- [ ] No : _please replace this line with details on why tests
      have not been included_

## [optional] Are there any post deployment tasks we need to perform?

invokeai/frontend/web/src/features/ui/components/tabs/ModelManager/subpanels/AddModelsPanel/ScanAdvancedAddModels.tsx

@@ -19,18 +19,16 @@ export default function ScanAdvancedAddModels() {
   const [advancedAddMode, setAdvancedAddMode] =
     useState<ManualAddMode>('diffusers');
 
-  const [isCheckpoint, setIsCheckpoint] = useState(
+  const [isCheckpoint, setIsCheckpoint] = useState<boolean>(false);
-    advancedAddScanModel &&
-      ['.ckpt', '.safetensors', '.pth', '.pt'].some((ext) =>
-        advancedAddScanModel.endsWith(ext)
-      )
-  );
 
   useEffect(() => {
-    isCheckpoint
+    advancedAddScanModel &&
+    ['.ckpt', '.safetensors', '.pth', '.pt'].some((ext) =>
+      advancedAddScanModel.endsWith(ext)
+    )
       ? setAdvancedAddMode('checkpoint')
       : setAdvancedAddMode('diffusers');
-  }, [setAdvancedAddMode, isCheckpoint]);
+  }, [advancedAddScanModel, setAdvancedAddMode]);
 
   const dispatch = useAppDispatch();