fix: make persistence failures terminal

[pathscale]

Summary

• add persisted composite-primary-key coverage across reload, range, update, delete, and graceful close
• add explicit Running/Closing/Closed/Failed persistence lifecycle state
• make wait_for_ops fallible and add consuming close() that drains and joins the engine
• stop applying later batches after terminal analyzer, event-gap, batch-apply, or engine-task failures
• reject later persistence and vacuum intake with the preserved root cause

Closes #36
Provides regression coverage for #15

Verification

• cargo clippy --all-targets -- -D warnings
• cargo test (137 unit passed; 337 integration passed; 3 existing ignored; doc tests passed)