fix: reload and atomically unlink firewall schedules (#537)

[thedancingdeveloper]

Summary

• reload firewall rules after schedule create/update/delete operations
• unlink deleted schedules from associated rules in the same transaction
• prevent rules from retaining dangling schedule references
• add API regression coverage for association and deletion behavior

Closes ZerosAndOnesLLC#537

Validation

• cargo fmt --all -- --check
• cargo clippy -p aifw-api --all-targets -- -D warnings
• cargo test -p aifw-api (171 passed)