2026.09.2

docs(release): document check workflow and migration (2026.09.2)

- README (zh/en): new read-only 'check' section covering state/policy
  blocks, runtime projection, budget measurement, TASK storage, exit
  codes, and legacy fail-closed behavior
- both SKILL.md packages: check bullet for adopted-project validation
- init/VERSION: 2026.09.1 -> 2026.09.2 (CalVer, sole bump this cycle)
- snapshots and embedded scripts regenerated via sync-skills.py
- includes a behavior-preserving git_toplevel -> git_in_worktree
  simplification in trellium.py (reflection-gate cleanup: the toplevel
  value was never consumed) plus a fix so bare-named task files
  (TASK-0001.md, no slug suffix) are discovered per the TASK-*.md glob
  instead of silently skipped under storage checks

Mechanical acceptance recorded on three temporary projects (fresh
adopt exit 0; legacy exit 0 with unresolved warnings; local storage
mismatch detection) and four ablation scenarios (remove state block,
remove policy block, flip runtime row, flip tracked/local).