v0.1.10

## What's Changed

### Per-project merged search index

- **`.mandex/` project directory** — `mx sync` now creates a `manifest.json` + `index.db` in your project root
- **Single FTS5 query** — merged index across all project packages instead of N separate DB queries
- **Smarter reranking** — only top-20 BM25 candidates reranked (not N×20)
- **`mx pull` / `mx remove`** automatically update the project manifest and rebuild the index

### Performance

| Scenario | v0.1.9 | v0.1.10 |
|----------|--------|---------|
| Project search (reranked) | 310ms | **70ms** |
| Single package | 40ms | **40ms** |
| Global fallback (no project) | 310ms | 310ms |