Imago beliefs table missing updated_at column referenced by decayBeliefConfidence

The decayBeliefConfidence() function in src/memory/consolidation.ts references updated_at column on the vesper_memory.beliefs table, but the migration 001-memory-schema.sql only defines created_at on that table. Running decayBeliefConfidence() against a fresh database created from migrations fails with a column-not-found error.