INSERT OR REPLACE resolved a secondary UNIQUE conflict by deleting a
different row (another PK) with capture suppressed and its ledger left live,
so a pair diverged silently (LocalDb-003). The applier now uses
INSERT ... ON CONFLICT(<pk>) DO UPDATE (DO NOTHING when every column is PK):
a clash on another unique key aborts the entry, which is dead-lettered, and
each node keeps its own row. Side effect: a remote update of a parent with
ON DELETE RESTRICT children now applies instead of being dead-lettered.
Also waits for the snapshot watermark in WipedPeer_SnapshotLiftsItsWatermark,
which raced SnapshotComplete under full-suite load.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty