Completes Phase 1 on top of the backend (43c798a7):
- Cross-source backfill: core/blocklist/backfill.py is a pure injected-resolver
core (resolve only missing sources, never raises); core/blocklist/runtime.py
wires the real metadata clients with a confident name-match (exact
significant-token equality; album/track also require the parent artist when
both expose one — no wrong IDs hung on an entry). Resolution runs
synchronously at add time, so a ban is cross-source from the first scan;
the artist name-fallback in matching covers any gap.
- API: GET/POST/DELETE /api/blocklist (profile-scoped) + /api/blocklist/search
(thin wrapper over the manual-match service search on the active source, so
the modal needn't know the source). Add resolves the other sources before
storing.
- Modal (webui/static/blocklist.js): tabbed Artists/Albums/Tracks in the
revamp design language (accent light-edge, pill tabs, debounced search with
spinner + out-of-order guard, per-result Block, "currently blocked" list
with a match-status star and per-row remove). Opened by a new "Blocklist"
button on the watchlist page, next to Download Origins.
Tests: 5 backfill (fill-missing-only, None/exception handling, arg shape) + 4
API (search proxy, add→backfill→list→delete round trip, validation). Modal
registered in the script-split onclick-coverage test; JS syntax-checked.