test(ci): add expiring flaky test registry

[luoye520ww]

Problem

Flaky test quarantine can become permanent when a record has no owner, issue, or expiry metadata.

Root cause

There was no bounded, machine-readable registry contract that CI could validate before consuming flaky-test records.

Scope

This PR adds the registry validator and CLI only. It does not change retry, quarantine, or CI execution behavior.

Changes

• Add versioned, bounded flaky-test registry validation.
• Require owner, issue reference, first-seen time, and future expiry.
• Reject duplicate test/platform records, unsupported fields, invalid timestamps, and out-of-range failure rates.
• Add a CLI that returns distinct invalid-registry and usage/JSON errors.
• Add focused Node tests for the contract boundaries.

Safety

• Registry input is bounded to 512 records and bounded string/number fields.
• Expiry requires an explicit timezone and must remain in the future.
• The validator is pure and does not modify CI state or test execution.

Typecheck

```text
npm.cmd run typecheck
```

Passed.

Tests

```text
node --test scripts/flaky-test-registry.test.cjs
node scripts/flaky-test-registry.cjs --file
node scripts/flaky-test-registry.cjs --file
npm.cmd run lint
npm.cmd run build
git diff --check
```

Results: 6 registry tests passed; valid fixture exited 0; invalid fixture exited 1; lint, build, and diff checks passed.

Review performed

• Functional correctness
• Input bounds and expiry lifecycle
• Error/CLI exit behavior
• Scope and compatibility
• Test quality

Non-goals

CI retry/quarantine integration and daily flaky-test pressure runs are intentionally deferred to follow-up PRs.

Part of the flaky-test registry work.

[luoye520ww]

The Linux packaged check is the same pre-existing guest-target timeout covered by #915; the registry code and typecheck passed. I am not duplicating the packaged smoke fix in this unrelated test registry PR. Please rerun after #915 lands.

[luoye520ww]

This work is consolidated into #941, which contains the related CI diagnostics and packaged smoke fix as one tested PR. Closing this duplicate to avoid parallel review and PR noise.