chore: add changeset for antfly migration

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: prosdev

.changeset/antfly-migration.md

@@ -0,0 +1,13 @@
+---
+"@prosdevlab/dev-agent-core": minor
+"@prosdevlab/dev-agent-cli": minor
+"@prosdevlab/dev-agent": minor
+---
+
+Replace LanceDB + @xenova/transformers with Antfly for hybrid search
+
+- **Hybrid search**: `dev_search` now uses BM25 + vector + RRF fusion — exact keyword matches AND semantic understanding in one query
+- **New command**: `dev setup` handles search backend installation (Docker-first, native fallback)
+- **Auto-embedding**: Antfly generates embeddings locally via Termite — no separate embedding pipeline
+- **Direct key lookup**: Replaces O(n) zero-vector scan with instant key fetch
+- **Breaking**: Requires Antfly server running (`dev setup` handles this). Existing LanceDB indexes are not migrated — run `dev index . --force` to rebuild.