fix(cookbook): Fix hf models not found in custom model directory

[AnghelRA]

Summary

If you add a custom model directory and add hf models in that directory, the models are not appearing on the web interface. I just add hf model scan to fix this behavior.

Target branch

• This PR targets dev, not main. All PRs land in dev; main is curated by the maintainer at each release. If your PR is on main by accident, click "Edit" on this PR and change the base.

Linked Issue

Fixes an issue related to #312

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)
• New feature (non-breaking — adds new behaviour)
• Breaking change (changes or removes existing behaviour)
• Refactor / cleanup (behaviour unchanged)
• Documentation only
• CI / tooling / configuration

Checklist

• I searched open issues and open PRs — this is not a duplicate.
• This PR targets dev
• My changes are limited to the scope described above — no unrelated refactors or whitespace changes mixed in.
• I actually ran the app (docker compose up or uvicorn app:app) and verified the change works end-to-end. Type-checks and unit tests are not enough.

How to Test

1. Go to cookbook and in Settings tab add a model directory
2. Go to launch tab and refresh cached models on selected server
3. The hf models in custom dir should be visible

Screenshots / clips

Cookbook Settings tab:

Before fix in Launch tab:

After fix in Launch tab: