ChromaBackend.close_palace() and close() evicted cached PersistentClients
from self._clients without calling client.close(), so chromadb 1.5.x kept
the rust-side SQLite file lock until GC. Reopening the same palace path
after shutil.rmtree + re-create within one process then failed with
SQLITE_READONLY_DBMOVED (SQLite code 1032).
Add _close_client() helper with a try/except fallback for older chromadb,
and route close_palace(), close(), and the DB-file-missing invalidation
branch of _client() through it. The mtime/inode auto-invalidation branch
is left as-is: callers there may still hold a live ChromaCollection
handle, and closing out from under them clears the rust bindings mid-use.
Regression tests cover close_palace reopen-same-path and whole-backend
close for multiple palaces.
mvalentsev
45df1a2657