Pagination: count_by_owner + count_search on AssetRepository,
timeline/search return real total count (not page len).
Auto-derivatives: worker enqueues GenerateDerivative when
ExtractMetadata job completes, closing the upload→thumbnail gap.
List endpoints: GET /albums, GET /stacks with user scoping.
ListAlbumsHandler, ListStacksHandler, find_by_owner on AssetStackRepository.
Tag filtering: tag_name field on AssetFilters, JOIN asset_tags+tags
in postgres search/count queries.
Bulk operations: POST /assets/bulk-delete, POST /assets/bulk-tag.
Album update: PUT /albums/{id} with UpdateAlbumHandler (title, description).
OpenAPI: utoipa annotations on all 47 endpoints + all request/response
schemas registered. Scalar UI at /scalar covers full API.
