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

vendor/modules.txt

@@ -167,22 +167,24 @@ github.com/vmihailenco/msgpack/v5/msgpcode
 github.com/vmihailenco/tagparser/v2
 github.com/vmihailenco/tagparser/v2/internal
 github.com/vmihailenco/tagparser/v2/internal/parser
-# golang.org/x/crypto v0.51.0
+# golang.org/x/crypto v0.53.0
 ## explicit; go 1.25.0
 golang.org/x/crypto/md4
-# golang.org/x/sync v0.20.0
+# golang.org/x/net v0.56.0
+## explicit; go 1.25.0
+# golang.org/x/sync v0.21.0
 ## explicit; go 1.25.0
 golang.org/x/sync/semaphore
-# golang.org/x/sys v0.44.0
+# golang.org/x/sys v0.46.0
 ## explicit; go 1.25.0
 golang.org/x/sys/cpu
 golang.org/x/sys/plan9
 golang.org/x/sys/unix
 golang.org/x/sys/windows
-# golang.org/x/term v0.43.0
+# golang.org/x/term v0.44.0
 ## explicit; go 1.25.0
 golang.org/x/term
-# golang.org/x/text v0.37.0
+# golang.org/x/text v0.39.0
 ## explicit; go 1.25.0
 golang.org/x/text/cases
 golang.org/x/text/encoding
@@ -202,8 +204,6 @@ golang.org/x/text/transform
 golang.org/x/text/unicode/bidi
 golang.org/x/text/unicode/norm
 golang.org/x/text/width
-# golang.org/x/tools v0.45.0
-## explicit; go 1.25.0
 # gopkg.in/yaml.v3 v3.0.1
 ## explicit
 gopkg.in/yaml.v3