feat(catalog): expose entityRef on Location type and add PUT /locations/:id

- Add `entityRef` field to all Location API responses, carrying the stable
  entity ref (e.g. `location:default/generated-<sha1hex>`) that was
  already persisted to the `location_entity_ref` column.
- Make `entityRef` filterable via `POST /locations/by-query`.
- Add `PUT /locations/:id` endpoint that updates the `type`/`target` of
  an existing location and issues the corresponding delta mutation so the
  catalog entity is updated in-place without changing its entity ref.
- Wire `updateLocation` through `CatalogApi`, `CatalogService`,
  `CatalogClient`, `LocationService`, `LocationStore`, and their
  implementations and mocks.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

plugins/api-docs/src/components/ApiExplorerPage/DefaultApiExplorerPage.test.tsx

@@ -58,7 +58,12 @@ describe('DefaultApiExplorerPage', () => {
         ],
       }),
     getLocationByRef: () =>
-      Promise.resolve({ id: 'id', type: 'url', target: 'url' }),
+      Promise.resolve({
+        id: 'id',
+        type: 'url',
+        target: 'url',
+        entityRef: 'location:default/generated-id',
+      }),
     getEntitiesByRefs: () => Promise.resolve({ items: [] }),
     getEntityFacets: async () => ({
       facets: { 'relations.ownedBy': [] },