Run Create Command
How vigilo run create validates run inputs, stores a recoverable creation plan,
seeds routed execution databases, and activates the run for dispatch.
The first control transaction assigns the durable run_id and records the run
as creating before any remote database commit. Placement seed writes are
idempotent. If immediate creation cannot finish, the command returns that same
run_id and its creation progress; a coordinator later claims the expired
creation lease and resumes the remaining placements. Dispatch cursors appear
only in the transaction that changes a fully seeded run to pending.