bug: vp install can finish work but hang without exiting after vp up -r --latest

### Reproduction

This seems to happen frequently after updating dependencies:

1. Run `vp up -r --latest`
2. Run `vp install`
3. Run `vp install` again if the lockfile/catalog state needs another pass after the update
4. The second `vp install` does all the work and appears finished, but the process does not exit

### Actual behavior

`vp install` appears done, but hangs instead of exiting cleanly.

### Expected behavior

Once install work is complete, `vp install` should exit normally.

### Notes

- This reproduces for me almost every time I update deps
- I just hit it on Codiff
- It used to happen on fate.technology as well

CC @fengmk2

Reproduce the hang by running `vp up -r --latest`, then repeating `vp install` as described, and confirm that the second command finishes work without exiting. Start from the `vp install` command entry point and trace the process after installation completes; done means the command exits normally in the reported dependency-update scenario.

索引モデルが issue の本文から書いたものです。