docs: update AGENTS.md and CHANGELOG for Trivy, Gitleaks, and cross-platform CI

Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>

Author: SebTardif

AGENTS.md

@@ -69,9 +69,9 @@ scripts/
     feature-request.yml    Feature request form
   PULL_REQUEST_TEMPLATE.md PR template
   workflows/
-    ci.yml                 CI: unit tests, build, integration tests (self-hosted)
+    ci.yml                 CI: unit tests (self-hosted + cross-platform matrix), build, integration tests
     dependabot-auto-merge.yml  Auto-merge minor/patch Dependabot PRs
-    security.yml           Security: npm audit (weekly + on push/PR)
+    security.yml           Security: npm audit, Trivy fs scan, Gitleaks (weekly + on push/PR)
 ```
 
 ## Architecture conventions

CHANGELOG.md

@@ -32,5 +32,8 @@
 
 - Automated test harness with unit tests and VS Code extension integration tests
 - CI on self-hosted runner with npm audit security scanning (weekly schedule)
+- Trivy filesystem vulnerability and misconfiguration scanning
+- Gitleaks secret detection across full commit history
+- Cross-platform unit test matrix (Ubuntu, Windows, macOS)
 - Dependabot auto-merge for minor and patch dependency updates
 - Extension packaging with `@vscode/vsce`