EFF-788: Support null K8s lastTransitionTime values

[tim-smart]

Summary

• Allow Kubernetes pod condition lastTransitionTime to decode as null in K8sHttpClient schemas
• Keep readiness initialization comparison compatible with null transition times
• Add regression test and changeset for @effect/cluster

Validation

• pnpm lint-fix
• pnpm test run packages/cluster/test/K8sHttpClient.test.ts
• pnpm check
• pnpm build
• pnpm docgen

[changeset-bot]

🦋 Changeset detected

Latest commit: 1dd0ae1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@effect/cluster	Patch
@effect/platform-bun	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/sql-clickhouse	Patch

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