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/golang.org/x/sys/unix/readv_unix.go

@@ -0,0 +1,103 @@
+// Copyright 2026 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || linux || openbsd
+
+package unix
+
+import "unsafe"
+
+// minIovec is the size of the small initial allocation used by
+// Readv, Writev, etc.
+//
+// This small allocation gets stack allocated, which lets the
+// common use case of len(iovs) <= minIovec avoid more expensive
+// heap allocations.
+const minIovec = 8
+
+// appendBytes converts bs to Iovecs and appends them to vecs.
+func appendBytes(vecs []Iovec, bs [][]byte) []Iovec {
+	for _, b := range bs {
+		var v Iovec
+		v.SetLen(len(b))
+		if len(b) > 0 {
+			v.Base = &b[0]
+		} else {
+			v.Base = (*byte)(unsafe.Pointer(&_zero))
+		}
+		vecs = append(vecs, v)
+	}
+	return vecs
+}
+
+// writevRaceDetect tells the race detector that the program
+// has read the first n bytes stored in iovecs.
+func writevRaceDetect(iovecs []Iovec, n int) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := min(int(iovecs[i].Len), n)
+		n -= m
+		if m > 0 {
+			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+}
+
+// readvRaceDetect tells the race detector that the program
+// has written to the first n bytes stored in iovecs.
+func readvRaceDetect(iovecs []Iovec, n int, err error) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := min(int(iovecs[i].Len), n)
+		n -= m
+		if m > 0 {
+			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+	if err == nil {
+		raceAcquire(unsafe.Pointer(&ioSync))
+	}
+}
+
+func Readv(fd int, iovs [][]byte) (n int, err error) {
+	iovecs := make([]Iovec, 0, minIovec)
+	iovecs = appendBytes(iovecs, iovs)
+	n, err = readv(fd, iovecs)
+	readvRaceDetect(iovecs, n, err)
+	return n, err
+}
+
+func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
+	iovecs := make([]Iovec, 0, minIovec)
+	iovecs = appendBytes(iovecs, iovs)
+	n, err = preadv(fd, iovecs, offset)
+	readvRaceDetect(iovecs, n, err)
+	return n, err
+}
+
+func Writev(fd int, iovs [][]byte) (n int, err error) {
+	iovecs := make([]Iovec, 0, minIovec)
+	iovecs = appendBytes(iovecs, iovs)
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	n, err = writev(fd, iovecs)
+	writevRaceDetect(iovecs, n)
+	return n, err
+}
+
+func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
+	iovecs := make([]Iovec, 0, minIovec)
+	iovecs = appendBytes(iovecs, iovs)
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	n, err = pwritev(fd, iovecs, offset)
+	writevRaceDetect(iovecs, n)
+	return n, err
+}