Add gstack with shared build for worktree support

[mzhaom]

Summary

• Pin gstack version via .gstack-version (commit hash, no submodule)
• scripts/setup.sh clones gstack to ~/.gstack/builds/<commit>/ and symlinks into the worktree — all worktrees share one ~300MB build
• .wt.yaml hook auto-runs setup on wt new/wt open/wt init
• Non-wt users run scripts/setup.sh once (documented in CLAUDE.md)

Test plan

• Run scripts/setup.sh on a fresh machine (no ~/.gstack/) — should clone, build, and symlink
• Run scripts/setup.sh again — should be near-instant (build cached)
• wt new test-gstack — should auto-setup via hook
• Verify ls -la .claude/skills/review resolves through symlink chain

🤖 Generated with Claude Code

---

Note

Medium Risk
Introduces a new setup script that clones/builds external code and writes symlinks under .claude/skills, which can affect developer environments and worktree behavior if the pinned commit or build steps change.

Overview
Adds pinned gstack integration for Claude skills via a new .gstack-version and an idempotent scripts/setup.sh that clones/fetches gstack, creates a shared worktree build under ~/.gstack/builds/<commit>, and symlinks gstack plus individual skills into .claude/skills/.

Configures worktree creation to auto-run setup via .wt.yaml, updates CLAUDE.md to document running scripts/setup.sh, and expands .gitignore to exclude the generated gstack/skill symlinks.

^{Written by Cursor Bugbot for commit a679f22. This will update automatically on new commits. Configure here.}

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.