session-recovery squashed migration

Trap: retaining generated intermediate recovery migrations or an intermediate schema.json.prevIds looks safer, but this unpublished feature has one 0→1 migration and intermediate lineage breaks clean-base generation. Fix: fold every schema change into 20260914170650_session-recovery, delete temporary migrations and registry entries, regenerate schema outputs from the immutable predecessor, and keep schema.json.prevIds at f14a9b18-8207-487e-a3d3-227e629ba9ad.