mutate_as and load now write directly to target tables and call the
publisher once at the end with per-table expected versions; the Run
state machine, _graph_runs.lance writers, __run__ staging branches,
and server /runs/* endpoints are removed. Multi-statement mutations
remain atomic at the manifest level via an in-memory MutationStaging
accumulator that gives read-your-writes within a query and a single
publish at the end. Concurrent-writer conflicts surface as
ExpectedVersionMismatch (HTTP 409 manifest_conflict) instead of the
old DivergentUpdate merge shape. Documents one known limitation in
docs/runs.md: a multi-statement mid-query failure where op-N writes
a Lance fragment and op-N+1 fails leaves Lance HEAD ahead of the
manifest until a follow-up introduces per-table Lance branches.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
