CodeBuddy adapter — all 21 skills ported and working

I've created a CodeBuddy adapter for gstack that ports all 21 skills to the CodeBuddy IDE.

**What it does:**
- All 21 skills work in CodeBuddy (`/office-hours`, `/review`, `/qa`, `/ship`, etc.)
- Browser automation (`/browse`) fully functional with Playwright
- One-line install: `git clone https://github.com/lndyzwdxhs/gstack.git ~/gstack && cd ~/gstack && ./setup --host codebuddy`
- Skills are symlinked to `~/.codebuddy/skills/skills/` so they stay up to date

**What I changed:**
- Added `--host codebuddy` flag to the setup script
- Adapted skill linking to CodeBuddy's skill directory structure
- Everything else (skill logic, browse binary, templates) is unchanged

**Repo:** https://github.com/lndyzwdxhs/gstack