chore(ci): add govulncheck, staticcheck, go vet, gofumpt gates

* Add lint/format checks to the Gitea release workflow and Makefile
  (targets: vet, fmt, fmt-check, staticcheck, govulncheck, check)
* Switch .golangci.json formatter from gofmt to gofumpt (extra.group-params)
* Bump golang.org/x/text 0.37.0 -> 0.39.0 for GO-2026-5970; re-vendor
* Fix staticcheck S1011 in pkg/diff; drop unused pgsql writer helpers
* Fix gocritic unnamedResult (pkg/diff) and rangeValCopy (pkg/pgsql)
* Apply gofumpt + goimports formatting across the tree

pkg/writers/drawdb/writer.go

@@ -48,7 +48,7 @@ func (w *Writer) writeJSON(data interface{}) error {
 	}
 
 	if w.options.OutputPath != "" {
-		return os.WriteFile(w.options.OutputPath, jsonData, 0644)
+		return os.WriteFile(w.options.OutputPath, jsonData, 0o644)
 	}
 
 	// If no output path, print to stdout