docs: add /gstack-submit to all skill lists and doc references

- README.md: added /gstack-submit to skills table, install skill lists
  (one-liner + add-to-repo + troubleshooting), added /design-shotgun
  and /connect-chrome to troubleshooting list, added PRIVACY.md to docs table
- CLAUDE.md: added gstack-submit/ to project structure tree
- docs/skills.md: added /gstack-submit to skills table

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

docs/skills.md

@@ -20,6 +20,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | [`/retro`](#retro) | **Eng Manager** | Team-aware weekly retro. Per-person breakdowns, shipping streaks, test health trends, growth opportunities. |
 | [`/browse`](#browse) | **QA Engineer** | Give the agent eyes. Real Chromium browser, real clicks, real screenshots. ~100ms per command. |
 | [`/setup-browser-cookies`](#setup-browser-cookies) | **Session Manager** | Import cookies from your real browser (Chrome, Arc, Brave, Edge) into the headless session. Test authenticated pages. |
+| [`/gstack-submit`](#gstack-submit) | **Community Showcase** | Submit your project to the gstack.gg gallery. Gathers build context, browses your deployed site, optionally reads Claude transcripts for the build story, writes a rich markdown entry with browser preview, then submits. |
 | | | |
 | **Multi-AI** | | |
 | [`/codex`](#codex) | **Second Opinion** | Independent review from OpenAI Codex CLI. Three modes: code review (pass/fail gate), adversarial challenge, and open consultation with session continuity. Cross-model analysis when both `/review` and `/codex` have run. |