Implements Phase 2a of board classifieds redesign: - GET/POST /api/board/posts (list with tag/author filters, create) - PATCH/DELETE /api/board/posts/:id (author-only) - GET /api/board/channels (member) - POST /api/admin/board-channels (admin) - PATCH/DELETE /api/admin/board-channels/:id (admin) Adds board_post_created activity type.
Model, schemas, API routes, activity log, and all server handlers updated. Old ecology/ and community-ecology routes removed, new board/ routes added. Tests updated and new board-suggestions tests written (10 cases).
