postgres-performancelisted

# PostgreSQL Performance Use only after the active phase identifies a PostgreSQL performance or capacity decision. Inherit its authority, artifact, review, proof, output, and completion contract; do not select a work mode or live database action here. Core invariant: connect a repeatable baseline to the limiting PostgreSQL resource and workload source, falsify the leading cause against its strongest competitor, then choose the smallest intervention with a comparable delta. Load one branch: - signal selection, attribution, plans, locks, I/O, WAL, vacuum, or replication -> [diagnostics.md](references/diagnostics.md); - query, index, statistics, pooling, maintenance, setting, or architecture change -> [interventions.md](references/interventions.md).