Stabilize Redis OOM CI check

[rblake2320]

What changed

• make the Redis noeviction/OOM integration check set maxmemory to a deterministic one-byte ceiling
• remove the racy used_memory snapshot calculation

Why

The same commit passed CI on master but intermittently failed on the freeze branch. Redis can reclaim memory between INFO memory and the authorization write, allowing the write to succeed even when the calculated ceiling was intended to force OOM.

Impact

Production behavior is unchanged. The CI safety check now deterministically verifies that authorization fails closed when Redis cannot persist nonce history.

Validation

• npm run build
• npm test (390 workspace tests)
• npm run test:pack
• npm run test:adversarial
• npm run test:interop
• npm audit --omit=dev
• Python client tests: 44 passed
• Python server tests: 37 passed
• npm run test:redis against real Redis: 20 consecutive passes

[rblake2320]

Verification status: ready

This change has completed code review and validation for the repository's current scope.

• GitHub Actions: Node and Python jobs passed for both push and pull-request events
• TypeScript workspace tests: 390 passed
• Python tests: 44 client + 37 server passed
• Real Redis integration: 20 consecutive passes
• Package boundary, adversarial, and cross-language interoperability checks passed
• Production dependency audit: 0 known vulnerabilities
• Pull request is mergeable

This records the repository as review-complete and CI-verified at commit 1f99631. It is a point-in-time verification, not a claim that future changes cannot introduce new issues.