hardening: migrate audit SQL helpers to prepared variants #48
Description
Problem
plugin_audit still has raw SQL helper usage (db_fetch_cell, db_fetch_assoc, db_execute) in setup/runtime paths.
Proposed change
- migrate straightforward call sites to prepared helper variants
- parameterize values currently interpolated into SQL where applicable
- preserve existing plugin behavior
Tests
- add regression checks for converted prepared helper usage in touched files
- run syntax checks for modified files and test script