toothpaste-kit 0.3.0

A MINOR release under docs/releasing.md: one new skill, and a release cadence.
Documentation and skill files only; no script changes.

Added

• skills/daily-review/. A once-a-day pass over a task board's lanes: the
  Inbox clarified to empty, carried work counted, finished work offered for
  close, priority read as an Eisenhower quadrant, and the day's order proposed.
  It proposes and asks; it moves nothing the person did not answer. It assumes
  a lane-board tool and says what that tool must print.
• docs/releasing.md has a Cadence section: a release review every two weeks
  on a Tuesday, with a Friday cutoff and a Monday final review, and a release
  only when the review admits one.

Changed

• CITATION.cff lists only the concept DOI, which is the one to cite. Each
  version DOI is recorded under "Where releases stand" in docs/releasing.md
  by the release after it, so a release no longer needs a follow-up pull
  request to record its DOI. Steps 3 and 7 of docs/releasing.md say so.
• README.md and docs/project-state.md list fifteen skills, with
  daily-review among those a person invokes.
• docs/quickstart.md: the example CLAUDE.md names the provenance layer and
  the file that lists the standing files, which the loop skills look for
  before writing.