Add a ce_pipeline_state machine (currentStage/status) kept distinct from
board-task ownership (task column) — separate tables, no shared column, per
FN-5719. onTaskMoved/onTaskCompleted hooks do only an indexed lookup + enqueue
and return well under the 5s budget; advancement happens in an on-demand
reconciler sweep that re-derives correct pipeline state from board truth, so a
dropped hook event still converges (no tight poll loop). Outbound CE-flow
changes create the next-stage board task. Conflict policy: board authoritative
for task state, CE flow authoritative for artifact/pipeline content (inbound
read and outbound write target different rows, so they cannot contend).
Host-scheduler note: no host timer wired; sweeps run on hook-drain and on the
dashboard/route refresh surface (tracked for the host event-publish follow-up).
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