test(integration): no cross-runtime coverage for health-check withdrawal and recovery

[dhyansraj]

The Python health check ships with integration coverage —
tests/integration/suites/uc02_agent_lifecycle/tc20_health_check_ttl_refresh,
tc21_health_check_lifespan_ready_gate, and the py-health-gate-agent /
py-health-recovery-agent artifacts. TypeScript (#1476) and Java (#1474) ship
none.

Everything currently asserted for TS is either a unit test with a stubbed
publish (health-check.spec.ts) or a Rust unit test that a command was
enqueued (napi.rs). Nothing exercises the chain the feature exists for:

healthCheck -> napi updateHealth -> heartbeat suppression -> registry
withdrawal -> consumer failover -> recovery via the 410 Gone re-register path

That chain was verified by hand for all three runtimes, but a manual E2E run is
not a regression guard.

To discuss before implementing

• Scope. Mirror tc20/tc21 for TypeScript only, or generalize the
  existing Python cases into a runtime-parameterized suite covering all three?
  The latter is more work but the three runtimes are meant to be behaviourally
  identical here, and divergence is exactly what we keep finding.
• Artifacts. New TS/Java agent images, or extend existing ones with an
  env-toggled failing check? Python used dedicated agents.
• Timing. These are slow tests — the withdrawal depends on the 20s registry
  staleness window, and recovery on the re-register path. Bounding them without
  fixed sleeps matters (see test(meshjob): gate tc16 on real job status instead of a fixed 8s sleep #1459).
• Release. Does 3.5.2 wait for this, or does it ship on the manual
  verification with the suite landing after?

Related: #1474, #1476.