docs: [#428] mark mysql triage subtask complete

Author: josecelano

docs/issues/428-docker-vulnerability-analysis-apr8-2026.md

@@ -122,7 +122,7 @@ For each image, execute these steps in order:
 
 #### 8. MySQL (`mysql:8.4`)
 
-- [ ] Analysis and triage completed
+- [x] Analysis and triage completed
 - [ ] Easy remediation implemented (if available)
 - [ ] Image rebuilt and validated
 - [ ] Trivy re-scan completed and compared