- Frontend Delete button (kanban.js) called DELETE /api/kanban/tasks/{id}
but no such route existed; FastAPI returned 405 Method Not Allowed,
so tasks (including 'done' ones) could never be deleted from the board.
- Added the missing route: removes the task's JSON file, cleans up any
links on other tasks that pointed to it (no orphaned parent/child
pointers), audits the action, returns {status:deleted}.
- Verified end-to-end against the running server (create -> delete -> 404).
Also captures current working state across brain/, skills/, agents/,
data/, tests/, and docs.