docs: update changelog with AWS account ID and security improvements

Author: burythehammer

CHANGELOG.md

@@ -2,6 +2,20 @@
 All notable changes to this project will be documented in this file.
 See updating [Changelog example here](https://keepachangelog.com/en/1.0.0/).
 
+## Unreleased
+
+### Added:
+* Added `AWSAccountID` field to `CloudDetail` struct in subscriptions model for AWS account identification
+* Added `govulncheck` to CI pipeline for automated vulnerability detection
+* New `.github/workflows/vulnerability.yml` workflow for parallel vulnerability checking
+* Enabled Go module caching in GitHub Actions for improved build performance
+
+### Updated:
+* Updated Go toolchain to 1.24.4 to address stdlib vulnerabilities (GO-2025-3751, GO-2025-3750, GO-2025-3749, GO-2025-3563)
+
+### Tests:
+* Added AWS account ID to subscription test fixtures (`TestSubscription_List`, `TestSubscription_Get`, `TestSubscription_Get_PublicEndpointAccess`)
+
 ## 0.40.0 (31st October 2025)
 
 ### Added: