fix: upgrade golangci-lint action to v7 with v2.1.6

CI was using golangci-lint v1 which doesn't support config version 2.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: rebelice

.github/workflows/ci.yml

@@ -47,9 +47,9 @@ jobs:
           go-version: '1.24'
 
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v4
+        uses: golangci/golangci-lint-action@v7
         with:
-          version: latest
+          version: v2.1.6
 
   build-multi-platform:
     name: Build (${{ matrix.os }})