fix(frontend): use query-form entity_id for metadata fetches

[larsgeorge-db]

Summary

Fixes a metadata-load failure on entity detail views (reproduced on the Data Domain detail page: a "Metadata load failed — Rich Texts fetch returned null or undefined data" toast).

Root cause

The entity metadata endpoints take the entity id as a query parameter (?entity_id=):

GET /api/entities/{entity_type}/rich-texts?entity_id={id}   (also links, documents, attachments)

but use-entity-metadata.ts and data-domain-details.tsx called them with the id as a path segment:

GET /api/entities/{entity_type}/{id}/rich-texts

Those URLs match no registered route, so they fall through to the SPA catch-all (@app.get("/{full_path:path}")), which returns 200 null for unmatched api/* paths. The domain view's checkApiResponse then treats null as an error and raises the toast.

(The shared entity-metadata-panel.tsx already used the correct query-form, which is why the panel works elsewhere.)

Fix

Switch both callers to the query-form the backend defines, URL-encoding the id (it may be an IRI). Update the hook tests to assert the query-form URLs.

Testing

• use-entity-metadata.test.ts: 31 passed; frontend typecheck clean.
• Verified in-app (Playwright): the Data Domain detail page renders with empty-state metadata sections and no error toast, 0 console errors.

Note

This is a pre-existing bug (lines date to Aug 3 / March), independent of any feature work. A follow-up worth considering separately: the SPA catch-all should return 404 for unmatched api/* paths instead of 200 null, so such mismatches fail loudly.