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/reflectutil/helpers.go

@@ -192,7 +192,7 @@ func mapKeyLess(a, b reflect.Value) bool {
 
 // MapGet safely gets a value from a map by key
 // Returns nil if key doesn't exist or not a map
-func MapGet(m interface{}, key interface{}) interface{} {
+func MapGet(m, key interface{}) interface{} {
 	v := reflect.ValueOf(m)
 	v, ok := Deref(v)
 	if !ok {