nibli

Work a single engine TODO item end-to-end — plan, implement, test/verify, then remove it from the tracker (or update it if only partially done), commit, and push to the nibli repo. Use for engine/runtime-crate tasks, one at a time (the book-manuscript variant is book-todo).

Work a single item from book/TODO.md end-to-end — plan, implement, test/verify, then remove it from TODO.md (or update it if only partially done), commit, and push to the book repo. Use for book-manuscript TODO items, one at a time (the engine variant is engine-todo).