feat: Review Readiness Dashboard + gstack-slug helper (v0.5.1) (#130)

* feat: add bin/gstack-slug helper + migrate all inline SLUG computation

Extract the opaque SLUG sed pipeline into a shared 5-line shell script.
Replace 8 inline copies across templates with eval $(gstack-slug).
Sanitizes branch names (/ → -) to prevent subdirectory creation.

* feat: review readiness dashboard — track CEO/Eng/Design reviews per branch

Each review skill logs its result to JSONL. A shared {{REVIEW_DASHBOARD}}
placeholder displays run counts, timestamps, and a CLEARED TO SHIP verdict.
/ship pre-flight reads the dashboard and prompts when reviews are missing.

* chore: bump version and changelog (v0.5.1)

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

ship/SKILL.md.tmpl

@@ -50,6 +50,15 @@ You are running the `/ship` workflow. This is a **non-interactive, fully automat
 
 3. Run `git diff <base>...HEAD --stat` and `git log <base>..HEAD --oneline` to understand what's being shipped.
 
+4. Check review readiness:
+
+{{REVIEW_DASHBOARD}}
+
+If the verdict is NOT "CLEARED TO SHIP (3/3)", use AskUserQuestion:
+- Show which reviews are missing or have open issues
+- RECOMMENDATION: Choose B (run missing reviews first) unless the change is trivial
+- Options: A) Ship anyway  B) Abort — run missing review(s) first  C) Reviews not relevant for this change
+
 ---
 
 ## Step 2: Merge the base branch (BEFORE tests)