feat(m9): todo/kanban with DnD, assignee notify, completion, tests, e2e
- TodoRepository (column CRUD, item CRUD, soft-delete, ordering, maxOrderIndex,
project isolation) + TodoService (lazy standard-column init, member/admin
permission, create/update/move/toggleComplete/delete, todo_assigned notify,
todo_created/updated/completed activity logs, SSE todo.updated)
- APIs: columns + items (GET/POST/PATCH/DELETE), toggleComplete + move
- KanbanBoard client (HTML5 drag&drop move, new task per column, complete),
todos page, ProjectNav ToDo link
- Unit tests (TodoRepository, TodoService) + e2e todo-kanban
385b251cc7