feat(media): add filename and readiness filters to shared listing

[FaiziNerd]

Closes #80

Summary

Larger repositories can now be narrowed in list_media / workspace without paging through the full catalog client-side.

ListMediaCommand accepts optional filename and state filters. The same semantics are projected through CLI (--filename, --state), HTTP (GET /media, GET /workspace), and MCP (list_media, get_workspace). Filtering runs in the existing SQLite media catalog (COUNT + LIST with the same predicates). Pagination and repository scoping are unchanged: cursors still encode offset in the current repository, and a filtered page uses the filtered total.

Filename matching is a case-insensitive substring of original_filename (so clip and CLIP both match Holiday-Clip.mp4). LIKE wildcards in the query are escaped. Readiness filtering uses the existing MediaState values (ready, pending, failed). The two filters combine. This is catalog lookup, not a second library index and not video-content search.

The browser UI lists ready media with state=ready so the registered-video picker does not mix incomplete or failed imports. No storage or index rebuild is required.

Test plan

• Catalog: filename substring (case-insensitive), state filter, combined filters, filtered pagination
• HTTP/CLI/MCP: filename and state are passed through ListMediaCommand with the same meaning
• Unfiltered listing and existing cursors still work
• Frontend registered-video list only requests ready media

Validation

uv run --no-sync ruff check .
uv run --no-sync pytest -q tests/test_media_catalog.py tests/test_media_services.py tests/test_api.py tests/test_cli.py tests/test_mcp.py tests/test_frontend.py

[tulayha]

Adding filters to workspace() makes the existing action calculation incorrect. page.total is now the filtered count, while indexed_media still contains every indexed media item in the repository. Comparing them can hide index_media even when later filtered results are not indexed. Please calculate workspace actions using consistent filtered or unfiltered values.

[tulayha]

The cursor is scoped only to the repository, so it can be reused with different filters. For example, a cursor from filename=clip can be sent with state=failed, and the failed-media results will start at the old offset and skip items. Please include filename and state in the cursor scope so a cursor is valid only for the query that created it.

[FaiziNerd]

Workspace action consistency
workspace() now computes index_media using repository-wide totals (consistent scope), so filtered page.total no longer hides indexing prompts.

Cursor/filter scoping
Pagination cursors are now filter-bound (filename + state), preventing reuse across different filter combinations and offset-skipping.

Frontend ready-only picker
The registered-video dropdown now requests only ready media (ListMediaCommand(..., state=MediaState.ready)), so pending/failed imports are excluded from selection.