fix(release): use inline grep for changelog gate, add v0.10.9 entry

The mage binary is not installed in the release CI runner and magefile.go
cannot be invoked with 'go run' due to its build tag. Replace with inline
grep which has no dependencies.

Co-authored-by: Copilot <[email protected]>

Author: jongio

.github/workflows/release.yml

@@ -118,7 +118,11 @@ jobs:
         env:
           RELEASE_VERSION: v${{ steps.version.outputs.version }}
         run: |
-          go run mage.go -w . ChangelogCheck
+          if ! grep -q "## \[${RELEASE_VERSION}\]" CHANGELOG.md; then
+            echo "::error::CHANGELOG.md has no entry for ${RELEASE_VERSION} -- add one before releasing"
+            exit 1
+          fi
+          echo "Found changelog entry for ${RELEASE_VERSION}"
 
       - name: Create and push tag
         run: |

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/), and this project adheres to [Semantic Versioning](https://semver.org/).
 
+## [v0.10.9] — 2026-06-07
+
+### Fixed
+- Release workflow changelog gate now uses inline grep (mage not available in CI runner)
+
 ## [v0.10.8] — 2026-06-07
 
 ### Fixed