Chameleon

Fixed

• A teach racing a profile re-derive is no longer silently lost. A
  (re-)bootstrap reads idioms.md and conventions.json early and carries
  those snapshots into the atomic profile swap, holding only .bootstrap.lock.
  teach_profile writes idioms.md under .idioms.lock and
  teach_competing_import / apply_archetype_renames write conventions.json
  (and renames.json) under .conventions.lock — disjoint locks. A teach that
  landed between the carry-read and the swap returned success but was then
  clobbered by the swap, with no integrity check to catch it. The refresh
  wrapper already guarded idioms.md with .idioms.lock, but the common
  /chameleon-refresh --force (and background auto-refresh) path left
  conventions.json exposed, and a direct bootstrap_repo(force=True)
  (/chameleon-init re-init) left idioms.md exposed. The (re-)derive now
  serializes against both teach write locks across its read-to-swap window, so
  a concurrent teach gets a clean "retry shortly" rejection instead of a silent
  loss. Locks are acquired in one fixed order everywhere (.idioms →
  .conventions → .bootstrap), so a refresh and a direct re-init cannot
  deadlock; verified under concurrent stress.