fix: custom components not loading with cjs extension

[FabienArcellier]

fix #405

---

This fix ensure vite build generates js files for custom components

> streamsync-ui@0.0.0 custom.build
> vite build --config vite.config.custom.ts

vite v5.2.8 building for production...
transforming...
✓ 11 modules transformed.
rendering chunks...
computing gzip size...
custom_components_dist/style.css         1.33 kB │ gzip: 0.44 kB
custom_components_dist/templates.umd.js  4.36 kB │ gzip: 1.68 kB
✓ built in 199ms

--- other minor changes

• the directory src/ui/custom_components_dist is in the ignored files of git
• the generated directories, ignore from git, are also ignored by eslint