docs: rewrite README + skills docs, auto-invoke /document-release (v0.8.4) (#207)

* docs: add 6 missing skills to proactive suggestion list

Add /codex, /careful, /freeze, /guard, /unfreeze, /gstack-upgrade to the
root SKILL.md.tmpl proactive suggestion list so Claude suggests them at
the appropriate workflow stages.

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

* docs: add 6 new skill entries + browse handoff to docs

- docs/skills.md: add /codex, /careful, /freeze, /guard, /unfreeze,
  /gstack-upgrade to skill table with deep-dive sections. Group safety
  skills into one "Safety & Guardrails" section. Add browse handoff
  subsection to /browse deep-dive.
- BROWSER.md: add handoff/resume to command reference table + section.

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

* docs: add power tools section + update skill lists in README

- Update prose: "Fifteen specialists and six power tools"
- Add power tools table after sprint specialists: /codex, /careful,
  /freeze, /guard, /unfreeze, /gstack-upgrade
- Update all 4 skill list locations (install Step 1, Step 2,
  troubleshooting CLAUDE.md example) to include all 21 skills

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

* docs: add v0.7-v0.8.2 features to README "What's new" section

Add paragraphs for browse handoff, /codex multi-AI review, safety
guardrails (/careful, /freeze, /guard), proactive skill suggestions,
and /ship auto-invoking /document-release.

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

* feat: auto-invoke /document-release after /ship PR creation

Add Step 8.5 to /ship that automatically reads document-release/SKILL.md
and executes the doc update workflow after creating the PR. This prevents
documentation drift — /ship now keeps docs current without a separate
command.

Completes P1 TODO: "Auto-invoke /document-release from /ship"

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

* chore: bump version and changelog (v0.8.4)

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

---------

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

SKILL.md

@@ -22,6 +22,12 @@ description: |
   - Ready to deploy / create PR → suggest /ship
   - Post-ship doc updates → suggest /document-release
   - Weekly retrospective → suggest /retro
+  - Wanting a second opinion or adversarial code review → suggest /codex
+  - Working with production or live systems → suggest /careful
+  - Want to scope edits to one module/directory → suggest /freeze
+  - Maximum safety mode (destructive warnings + edit restrictions) → suggest /guard
+  - Removing edit restrictions → suggest /unfreeze
+  - Upgrading gstack to latest version → suggest /gstack-upgrade
 
   If the user pushes back on skill suggestions ("stop suggesting things",
   "I don't need suggestions", "too aggressive"):