test: E2E tests for plan review report and Codex offering (v0.11.15.0) (#449)

* chore: regen SKILL.md from template changes

Regenerated via `bun run gen:skill-docs` — was stale from prior
template updates (Codex paths, preamble resolver).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test: add E2E tests for plan review report and codex offering

- plan-review-report: verifies plan-eng-review writes ## GSTACK REVIEW
  REPORT to the bottom of the plan file
- codex-offered-{office-hours,ceo-review,design-review,eng-review}:
  verifies each skill has Codex availability check, user prompt, and
  fallback behavior (4 concurrent lightweight tests)
- Updated touchfiles and selection count assertion

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add touchfiles to global touchfile list in CLAUDE.md

The touchfiles.ts file itself is a global touchfile that triggers all
tests when changed, but was missing from the documented list.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.11.15.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-0.11.14.0
+0.11.15.0