Add unit tests for UserProjectSectionComponent

### Task Summary

`UserProjectSectionComponent` currently has no spec. Add Vitest unit coverage for its route-driven project loading (`ngOnInit` URL-segment handling, `retrieveProject`/`getProjectList`), project color update/removal against the real `isLightColor`/`isInvalidColorFormat` statics, and project-file access.

### Task Type

- [x] Testing / QA

Locate UserProjectSectionComponent and the existing Vitest setup, then inspect related component specs and the project-loading entry points. Add coverage for ngOnInit URL-segment handling, retrieveProject/getProjectList, color updates and removal using the named statics, and project-file access; done means these behaviors are covered by passing unit tests.

Written by the indexing model from the issue text.