Adds /peertube/review page showing only tied_manual items for human
domain assignment. Each row displays video title, channel, concept
domain counts, and a dropdown to select the correct domain.
Routes: GET /peertube/review (page), GET /api/peertube/review/items
(JSON), GET /api/peertube/review/stats (counts),
POST /api/peertube/review/assign (assign + push to PeerTube).
Review subnav entry added to PEERTUBE_SUBNAV.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
