History writes deliberately give up after a bounded 250 ms wait so they
never stall ComfyUI; the existing bounded-timeout test still proves that.
The concurrent replay tests assert that every peer succeeds, which is a
serialization and first-capture property, so they now raise the budget
to the shared 30 s busy timeout while the first writer is held open.
The budget is one named constant, EXECUTION_BUSY_TIMEOUT_MS, shared by
the transaction helper and the background writer.
Before: 20/20 'database is locked' with the held writer. After: 0/20.
The concurrent replay tests expected every peer to succeed, but each peer
only waits 250 ms for BEGIN IMMEDIATE by design. On a slow Windows runner
three queued commits exceeded that and a peer raised 'database is
locked'. Holding the first writer's transaction open for 500 ms makes the
same failure deterministic on any host (20/20 locally).