refactor: update health server port handling and enhance library page layout

Commit notes

- Simplified health server port configuration to prioritize WORKER_HEALTH_PORT. - Refactored library page to improve loading, error, and empty states for samples. - Removed LibraryFilters component to streamline the library interface. - Adjusted filter popover position and button styles for better UI consistency.

Files modified: - backend/src/worker.ts - frontend/src/routes/library/+page.svelte - frontend/src/routes/library/components/LibraryFilters.svelte (deleted) - frontend/src/routes/library/components/LibrarySearchFilter.svelte