feat(runtime): add durable Gate B memory authorization

[DanielJD1216]

Summary

• add PostgreSQL 16-backed Gate B memory-only clients, sessions, namespace/capability grants, authorization epochs, deletion epochs, and sender-key-wide DPoP replay consumption
• add durable authorization derived exclusively from PostgreSQL state, with bounded lock and statement waits and no process-local fallback
• reauthorize immediately before protected-read receipt consumption using canonical prepare-lock-authorize-consume ordering, then clear protected results and serialized buffers on every denied or failed release
• preserve replay denial for the full proof window across originating-session expiry, processes, pool teardown, and restart
• preserve immutable historical restore receipts across schema 6 to 7 migration while new schema-7 operations remain current
• keep the durable authority unreachable from HTTP, stdio, MCP, server, app, and runtime composition, enforced by exact changed-path and mutation gates
• update the live owner-open-issue boundary from merged Gate B: synthetic memory-only access-plane implementation #288 to active approved Gate B: durable memory-only authorization and release recheck #290

Closes #290.

Scope boundary

This is a synthetic Gate B-M durability slice. It does not complete Gate B exit and does not authorize production testing or deployment.

Included:

• disposable PostgreSQL 16 only
• synthetic identities, sender-proof metadata, credentials, and trusted memory
• durable replay, session, grant, credential, epoch, and release-time authorization state
• successful and denied protected-read receipt paths
• PostgreSQL role, function, ACL, migration, race, outage, restart, and cleanup proof

Not included or authorized:

• OAuth/OIDC integration or signed access-token verification
• cryptographic DPoP JWT parsing, signature verification, or nonce issuance
• TLS or mTLS handshake and certificate-chain validation
• Streamable HTTP MCP or any network listener
• evidence mode, PostgreSQL 18, model service, or live connectors
• deployment, private data, team access, production activation, package publication, release, or managed hosting

Verification

• npm run alpha1:conformance (42 / 38 / 23 / 26 / 30 / 30)
• npm run alpha1:conformance:evidence-first (32/32)
• npm run local-runtime:candidate-conformance
• npm run alpha1:test (186/186)
• npm run runtime:gate-b-memory-only (31/31)
• npm run runtime:gate-b-memory-only:scope
• npm run runtime:gate-b-memory-only:scope:smoke
• npm run ci:check
• npm run publish:readiness
• npm run package:dry-run
• npm run owner:open-issues-status
• npm run owner:open-issues-status:smoke
• npm run docs:command-setup
• git diff --check

Safety scan: 0 findings. Claims scan: 0 findings.

Review notes

• initial independent review blocked sender-wide replay expiry at session end and schema-6 restore-receipt incompatibility
• both blockers were fixed with real PostgreSQL conformance cases
• additional hardening added release prelocking, fresh-time linearization, bounded DB waits, full Gate B table ACL verification, all three SECURITY DEFINER function checks, oversized bigint denial, successful durable retrieval/consumption proof, and custom-executor receipt-consumption enforcement
• final exact-tree security and TDD review completed before commit
• Gate B-M exit, Gate C operation, target-setup testing, deployment, and private data remain blocked