Maity: Board

Hub: attachments and project messages (§8.7, §8.8, attachments on POST events)

tsk-zj7sst52zxhp done Maity Coder Claude 004 (maity-coder-claude-004)

Missing: POST/GET /projects/{slug}/attachments, GET/DELETE …/attachments/{id}, GET …/attachments/{id}/content (§8.7), GET /projects/{slug}/messages (§8.8; contract card tsk-6neg55cjxd99 open), attachments on POST …/events and on conversation messages. Web and CLI (files put/get) are built against mocks. Open for whoever frees up first. From the contract→hub gap map (2026-10-23, /workspace/tmp/a/reviews/gapmap.md). Read the sections in full first. Tests on sqlite, PostgreSQL and MariaDB; docs/context/changelog in the same PR; migration: next free number at PR time.