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

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/stretchr/testify v1.11.1
 	github.com/uptrace/bun v1.2.18
 	github.com/uptrace/bun/dialect/pgdialect v1.2.18
-	golang.org/x/text v0.37.0
+	golang.org/x/text v0.39.0
 	gopkg.in/yaml.v3 v3.0.1
 	modernc.org/sqlite v1.50.1
 )
@@ -42,11 +42,11 @@ require (
 	github.com/tmthrgd/go-hex v0.0.0-20190904060850-447a3041c3bc // indirect
 	github.com/vmihailenco/msgpack/v5 v5.4.1 // indirect
 	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
-	golang.org/x/crypto v0.51.0 // indirect
-	golang.org/x/sync v0.20.0 // indirect
-	golang.org/x/sys v0.44.0 // indirect
-	golang.org/x/term v0.43.0 // indirect
-	golang.org/x/tools v0.45.0 // indirect
+	golang.org/x/crypto v0.53.0 // indirect
+	golang.org/x/net v0.56.0 // indirect
+	golang.org/x/sync v0.21.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
+	golang.org/x/term v0.44.0 // indirect
 	modernc.org/libc v1.72.3 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect