ci: add go vet job to PR workflow

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -27,3 +27,12 @@ jobs:
         with:
           go-version-file: go.mod
       - run: go test ./...
+
+  vet:
+    runs-on: linux
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+      - run: go vet ./...