Migrate the STATE.md write path inside cmdMilestoneComplete (milestone.cts)
onto the STATE.md Transition Module substrate (ADR-1769, epic #1769).
- Add {kind: 'milestoneComplete'} to StateTransitionIntent, with
milestoneCompleteCore in src/state-transition.cts (consulting the
field-classification table). Owns the closure write: Status
('<version> milestone complete'), Last Activity, Last Activity Description,
a Current Position reset to 'Awaiting next milestone', and an Operator Next
Steps reset pointing at the next-milestone command.
- Collapse the inline STATE.md transform in cmdMilestoneComplete to a
transitionCore dispatch. The adapter retains writeStateMd (lock + steady-state
syncStateFrontmatter post-sync) and resolves the runtime-specific
next-milestone slash command, injecting it via intent.nextMilestoneCommand.
- The two section resets carry their pre-seam allow-adhoc-markdown waivers
(regex semantics pinned by existing tests; pending collectSection #1372).
- realClock.today() is byte-identical to milestone.cts's local today
(both new Date().toISOString().split('T')[0]).
- Characterization tests pin field updates, both section resets (replace +
insert paths), and frontmatter #1255 parity.
All 66 transition + milestone + state tests pass.
Closes#1789
3ceb83329d