fix: add retry support for health checks

[naufalfx805-source]

Summary

Adds configurable retry/backoff support for transient HTTP and TCP health-check failures so temporary connection refused or timeout conditions can recover before returning CRITICAL.

Closes #2.

Changes

• Added --retries and --retry-backoff CLI flags.
• Retries retryable HTTP/TCP exceptions such as connection refused and timeouts.
• Preserves single-attempt behavior by default with --retries 0.
• Adds attempts and latency_ms metadata to JSON health-check output.
• Adds tools/health_check_retry_harness.py covering success-after-retry, exhausted-retry, and JSON retry metadata.

Testing

Ran locally:

python -m py_compile tools/health_check.py tools/health_check_retry_harness.py
python tools/health_check_retry_harness.py
python tools/health_check.py --help
python tools/health_check.py --service postgresql --json --retries 1 --retry-backoff 0
python -X utf8 build.py

Results:

• py_compile passed.
• Retry harness passed: health check retry harness passed.
• CLI help shows --retries and --retry-backoff.
• JSON output includes attempts and latency_ms.
• python build.py initially hit Windows console encoding for the warning symbol, so I reran with python -X utf8 build.py.
• Build then reached diagnostics but failed environment preflight because encryptly could not create a .logd artifact in this local environment. The generated diagnostic JSON is committed at diagnostic/build-3d7f3362.json and records the blocker.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

---

• I would like to request that my diagnostic build log is removed before merging

[naufalfx805-source]

This PR addresses the health check retry support described in the original issue scope. Ready for review. 🚀