fix: pin golangci-lint v2.4 for Go 1.25 compatibility

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: tjp2021

.github/workflows/ci.yaml

@@ -14,9 +14,9 @@ jobs:
       - uses: actions/setup-go@v5
         with:
           go-version: "1.25"
-      - uses: golangci/golangci-lint-action@v6
+      - uses: golangci/golangci-lint-action@v7
         with:
-          version: latest
+          version: v2.4
 
   test:
     runs-on: ${{ matrix.os }}