The Qdrant _TableShim returned updated_at as ISO strings (not datetime
objects), causing str.replace(tzinfo=...) to fail with
"str.replace() takes no keyword arguments". Parse strings via
datetime.fromisoformat() before timezone handling.
Also add missing delete(where) and update(where=, values=) methods to
_TableShim so the LanceDB-compatible shim works with Qdrant's payload
collection, plus a _parse_where() helper to convert where clauses to
Qdrant Filters.
