feat(security): land Engram 10/10 waves 0-2 foundations

[limaronaldo]

Summary

• establish Wave 0 contract, baseline, release-policy, and transport fixtures
• complete Wave 1 principal, durable-key, advisory, and real-server foundations
• close Wave 2 fail-closed HTTP/WebSocket/gRPC security, durable cloud rotation, SQLite filesystem hardening, and bounded PDF isolation
• record the immutable Wave 2 barrier v4 and independent review v2 PASS

Verification

• Wave 2 barrier v4: 21/21 gates PASS, no exclusions
• make ci and full harness sensors
• real-binary HTTP/SSE, WebSocket/listener, and gRPC suites
• focused cloud, SQLite, and PDF suites
• no-default and all-features workspace checks
• advertised-contract, packaging, MCP-reference, audit, deny, and governed-exception checks
• cargo package and cargo publish --dry-run only
• independent review v2: PASS

Limitations

• FreeBSD/OpenBSD runtime behavior was not executed on the macOS verifier host; shared strict /dev/fd/<digits> recognition has unit coverage
• this PR performs no tag, release, real publication, or channel approval
• later Engram 10/10 waves remain out of scope

Evidence

• candidate before closeout: 98b844680ee569df5f9254e7f5e2e9e51e59c900
• base: 9b832146a3c3cc326aaa9e12d0e72de679e7f75f
• barrier: .omo/evidence/wave-2-integration-barrier-v4.md
• review: docs/harness/reviews/2026-07-12-engram-10-of-10-wave2-v2-post.md

[huly-for-github]

Connected to Huly®: ENGRA-225