Why: D49/D51 — aggregated project view (project cards + other
conversations' pending) so todos survive conversation switches;
D50 — subscribe the project channel via scope=project.
Evidence: api endpoints (listProjectCards/cardToProject, card.* named
SSE events — also fixes live card events previously dropped);
store projectCards/inboxScope/applyProjectEvent/cardToProject with
badge combining both scopes; Workbench scope tabs + grouped ProjectInbox;
styles for scope control.
Impact: existing conversation inbox behavior unchanged; badge now counts
both scopes.
Refs: documents proposal 2026-09-30-card-stream-artifact-unify-project-inbox.md (D48-D51).