chore: skip and remove upstream-only project configs

Add to skipFiles and remove:
- `.opencode/tool/github-triage.*`, `github-pr-search.*` — upstream team triage tools
- `.opencode/agent/duplicate-pr.md`, `triage.md`, `docs.md` — upstream agents
- `.opencode/themes/mytheme.json` — upstream dev's personal theme
- `.opencode/env.d.ts` — types for upstream plugins
- `.opencode/command/rmslop.md`, `ai-deps.md`, `spellcheck.md` — upstream dev commands
- `script/sync-zed.ts` — Zed extension sync (no workflow references it)
- `AGENTS.md` — references `dev` branch, misleading for our fork

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

Author: anandgupta42