e200ce2c8a
When external tools write to the palace database (CLI mining, scripts), the MCP server's cached ChromaDB collection becomes stale — its HNSW index doesn't know about new vectors. Develop already invalidates on inode changes (catches rebuilds) but not on mtime changes (misses in-place writes). This PR: - Adds st_mtime tracking alongside st_ino in _get_client; invalidates the cached client on either change. - Adds the mempalace_reconnect MCP tool for explicit cache flush. Original author: @jphein (#663). Original approval: @Ari4ka. Skips test_missing_db_invalidates_cache on Windows (ChromaDB holds chroma.sqlite3 open).