Per-task workflow

Full canonical version lives in _docs/WORKFLOW.md; the shape is:

1. Pick the next unblocked task.
2. Read the chunk's "Done when:" criteria in the milestone doc.
3. Mark in_progress (one task at a time).
4. Implement the smallest change that satisfies the contract.
5. Test — unit / snapshot / integration / property as appropriate.
6. CHECK — just gate must be green before close.
7. UPDATE — append to PROGRESS.md; file new issues in ISSUES.md.
8. Mark completed and confirm next task is unblocked.
9. Commit at natural boundaries (typically one chunk = one commit).

If the chunk is renderable, also:

• Add a story to the appropriate storybook (wisp-storybook or ui-storybook).
• Run just snapshots to regenerate the asset under _docs/book/src/assets/<crate>/<id>.{png,html}.
• Reference the asset from the chunk's mdBook page.

If the chunk introduces public API:

• Add /// doc to every new public item (missing_docs enforces it).
• Update the crate's //! header if the architecture changed.
• At least one # Examples doctest on each new public function.