feat: unify plugin-lib repo ref + add ingest mutex #96

[four-bytes-robby]

Closes #96

Changes

• Phase 2: Update package.json dependency from github:four-bytes/opencode-plugin-lib → github:four-bytes/four-opencode-plugin-lib (unified canonical name)
• Phase 3: Add src/ingest/mutex.ts — in-process Promise-based ingest queue that serializes all ingest runs (auto-ingest + manual /brain ingest) to prevent SQLITE_BUSY from concurrent writes

Verification

• bun run build passes
• bun install resolves new repo URL correctly

---

Summary by cubic

Unifies the @four-bytes/opencode-plugin-lib repo reference and adds an in-process ingest mutex to prevent SQLITE_BUSY during concurrent ingests. Closes #96.

• Bug Fixes

  • Serialize all ingest runs (auto + /brain ingest) with an in-process Promise mutex to avoid concurrent writes.

• Dependencies

  • Point @four-bytes/opencode-plugin-lib to github:four-bytes/four-opencode-plugin-lib#v0.2.0 (canonical repo).

^{Written for commit e927b06. Summary will update on new commits.}