fix: resolve merge conflicts with origin/main (v0.4.3 + v0.4.4)

Merge origin/main which added:
- v0.4.3: /document-release skill, simplified AskUserQuestion (always ELI16),
  runtime branch detection via _BRANCH preamble variable
- v0.4.4: 60-min update check TTL, --force flag for gstack-update-check

Resolved conflicts:
- VERSION: keep 0.6.0 (our version, above 0.4.4)
- CHANGELOG: all entries preserved (0.6.0 > 0.4.4 > 0.4.3 > 0.4.2)
- TODOS.md: keep both sections (Brainstorm/Design + Document-Release)
- test/skill-validation.test.ts: include all three new skills in arrays
  (brainstorm, debug, document-release)

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

review/SKILL.md.tmpl

@@ -168,6 +168,20 @@ If TODOS.md doesn't exist, skip this step silently.
 
 ---
 
+## Step 5.6: Documentation staleness check
+
+Cross-reference the diff against documentation files. For each `.md` file in the repo root (README.md, ARCHITECTURE.md, CONTRIBUTING.md, CLAUDE.md, etc.):
+
+1. Check if code changes in the diff affect features, components, or workflows described in that doc file.
+2. If the doc file was NOT updated in this branch but the code it describes WAS changed, flag it as an INFORMATIONAL finding:
+   "Documentation may be stale: [file] describes [feature/component] but code changed in this branch. Consider running `/document-release`."
+
+This is informational only — never critical. The fix action is `/document-release`.
+
+If no documentation files exist, skip this step silently.
+
+---
+
 ## Important Rules
 
 - **Read the FULL diff before commenting.** Do not flag issues already addressed in the diff.