[dr-dimitru]

Summary

• Report unfinished interval and one-shot handlers; preserve at-most-once one-shot behavior.
• Repeated shutdown calls share the first attempt.
• Report superseded handlers without releasing obsolete claims.
• Includes the fencing branch dependency; merge after its PR.

Verification

• Full npm test with local Redis, MongoDB, PostgreSQL passed.
• 182 Jest tests passed; 20 environment-specific tests skipped.
• Regression checks and generated build passed.