fix(cable-health): close cache publication race

[koala73]

Summary

• keep the public cable-health cache positive-only while preserving NGA negative caching
• await fallback and seed metadata publication before returning the fallback
• add a regression test for the former health EMPTY race and valid zero-cable data

Verification

• node_modules/.bin/tsx --test tests/cable-health-cache-race.test.mts tests/handlers.test.mts tests/redis-caching.test.mjs
• npm run typecheck:api
• npm run lint:boundaries
• npm run lint
• git diff --check

Scope

No seeder, grace, threshold, scoring, or production-operation changes. Production deployment and live acceptance remain outside this PR.

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Project	Deployment	Actions	Updated
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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-03T14:42:06.820151Z	1218a2a	PR opened

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