Add durable collective control adapters

[douglas-grishen]

Stacked Beta 2 increment 4.

• adds authority-neutral Room mandate proposals and digest-only evidence projections
• adds @agentplat/collective-control-postgres with additive migration 1
• implements scoped authority/execution CAS, durable Action Grants, evidence chains, integrity verification, retention and rollback readiness
• documents expand/recovery/rollback operations

Verification:

• affected builds and type checks
• public contract type checks
• collective control, governed actions, Mesh and Rooms tests
• PostgreSQL 16.11 integration with concurrency and injected transaction/response-loss faults
• public-surface release audit
• isolated npm pack for the new adapter

The coordinated Beta 2 version/pack gate remains in the final release increment.