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>

CLAUDE.md

@@ -29,7 +29,7 @@ against the previous run.
 **Diff-based test selection:** `test:evals` and `test:e2e` auto-select tests based
 on `git diff` against the base branch. Each test declares its file dependencies in
 `test/helpers/touchfiles.ts`. Changes to global touchfiles (session-runner, eval-store,
-llm-judge, gen-skill-docs) trigger all tests. Use `EVALS_ALL=1` or the `:all` script
+llm-judge, gen-skill-docs, touchfiles) trigger all tests. Use `EVALS_ALL=1` or the `:all` script
 variants to force all tests. Run `eval:select` to preview which tests would run.
 
 ## Testing