New `/libraries` endpoint returns configured libraries so clients can
discover them. `FilesRequest` and `MemoriesRequest` gain an optional
`library` param (accepts name or numeric id). Unknown values are
rejected with 400; absent values span all libraries. `/memories`
now scopes its filesystem walk + EXIF query to the resolved library.
`MemoryItem` carries `library_id` so union-mode clients can render a
per-item source badge.
Behavior is unchanged in single-library mode: omitting `library` still
returns results from the primary library, which is the only one
configured until a second row is added to the libraries table.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Adds a `libraries` registry table and threads library_id through
per-instance metadata tables (image_exif, photo_insights,
entity_photo_links, video_preview_clips). File-path columns renamed to
rel_path to make the relative-to-root semantics explicit. Adds
content_hash + size_bytes on image_exif to support future hash-keyed
thumbnail/HLS dedup. Tags and favorites stay library-agnostic so they
share across libraries by rel_path.
Behavior is unchanged: a single primary library (id=1) is seeded from
BASE_PATH on first boot; all handlers and DAOs route through it as a
transitional shim until the API gains a library query param.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
