chore(ci): bump golangci-lint action to v9

Update the GitHub Actions CI workflow to use golangci/golangci-lint-action@v9 instead of v8. This keeps the lint job aligned with the latest major version and ongoing action maintenance.

.github/workflows/ci.yml

@@ -113,7 +113,7 @@ jobs:
       - name: Stub internal/web/dist for go:embed
         run: mkdir -p internal/web/dist && touch internal/web/dist/.gitkeep
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v8
+        uses: golangci/golangci-lint-action@v9
         with:
           version: latest