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/text/unicode/norm/forminfo.go

@@ -121,8 +121,12 @@ func (p Properties) BoundaryAfter() bool {
 //
 // When all 6 bits are zero, the character is inert, meaning it is never
 // influenced by normalization.
+//
+// We set flags to 0x80 (high bit 7 unused in quick check data) to indicate an invalid rune.
 type qcInfo uint8
 
+func (p Properties) isInvalid() bool { return p.flags == 0x80 }
+
 func (p Properties) isYesC() bool { return p.flags&0x10 == 0 }
 func (p Properties) isYesD() bool { return p.flags&0x4 == 0 }
 
@@ -247,6 +251,9 @@ func (f Form) PropertiesString(s string) Properties {
 // to a Properties.  See the comment at the top of the file
 // for more information on the format.
 func compInfo(v uint16, sz int) Properties {
+	if sz == 0 {
+		return Properties{flags: 0x80, size: 1}
+	}
 	if v == 0 {
 		return Properties{size: uint8(sz)}
 	} else if v >= 0x8000 {
@@ -254,7 +261,7 @@ func compInfo(v uint16, sz int) Properties {
 			size:  uint8(sz),
 			ccc:   uint8(v),
 			tccc:  uint8(v),
-			flags: qcInfo(v >> 8),
+			flags: qcInfo(v>>8) & 0x3f,
 		}
 		if p.ccc > 0 || p.combinesBackward() {
 			p.nLead = uint8(p.flags & 0x3)

vendor/golang.org/x/text/unicode/norm/iter.go

@@ -376,16 +376,12 @@ func nextComposed(i *Iter) []byte {
 			goto doNorm
 		}
 		prevCC = i.info.tccc
-		sz := int(i.info.size)
-		if sz == 0 {
-			sz = 1 // illegal rune: copy byte-by-byte
-		}
-		p := outp + sz
+		p := outp + int(i.info.size)
 		if p > len(i.buf) {
 			break
 		}
 		outp = p
-		i.p += sz
+		i.p += int(i.info.size)
 		if i.p >= i.rb.nsrc {
 			i.setDone()
 			break

vendor/golang.org/x/text/unicode/norm/normalize.go

@@ -148,7 +148,7 @@ func (f Form) IsNormalString(s string) bool {
 // patched buffer and whether the decomposition is still in progress.
 func patchTail(rb *reorderBuffer) bool {
 	info, p := lastRuneStart(&rb.f, rb.out)
-	if p == -1 || info.size == 0 {
+	if p == -1 || info.isInvalid() {
 		return true
 	}
 	end := p + int(info.size)
@@ -225,7 +225,7 @@ func doAppend(rb *reorderBuffer, out []byte, p int) []byte {
 	}
 	fd := &rb.f
 	if doMerge {
-		var info Properties
+		info := Properties{flags: 0x80, size: 1} // invalid rune
 		if p < n {
 			info = fd.info(src, p)
 			if !info.BoundaryBefore() || info.nLeadingNonStarters() > 0 {
@@ -235,7 +235,7 @@ func doAppend(rb *reorderBuffer, out []byte, p int) []byte {
 				p = decomposeSegment(rb, p, true)
 			}
 		}
-		if info.size == 0 {
+		if info.isInvalid() {
 			rb.doFlush()
 			// Append incomplete UTF-8 encoding.
 			return src.appendSlice(rb.out, p, n)
@@ -314,7 +314,7 @@ func (f *formInfo) quickSpan(src input, i, end int, atEOF bool) (n int, ok bool)
 			continue
 		}
 		info := f.info(src, i)
-		if info.size == 0 {
+		if info.isInvalid() {
 			if atEOF {
 				// include incomplete runes
 				return n, true
@@ -379,7 +379,7 @@ func (f Form) firstBoundary(src input, nsrc int) int {
 	// CGJ insertion points correctly. Luckily it doesn't have to.
 	for {
 		info := fd.info(src, i)
-		if info.size == 0 {
+		if info.isInvalid() {
 			return -1
 		}
 		if s := ss.next(info); s != ssSuccess {
@@ -424,7 +424,7 @@ func (f Form) nextBoundary(src input, nsrc int, atEOF bool) int {
 	}
 	fd := formTable[f]
 	info := fd.info(src, 0)
-	if info.size == 0 {
+	if info.isInvalid() {
 		if atEOF {
 			return 1
 		}
@@ -435,7 +435,7 @@ func (f Form) nextBoundary(src input, nsrc int, atEOF bool) int {
 
 	for i := int(info.size); i < nsrc; i += int(info.size) {
 		info = fd.info(src, i)
-		if info.size == 0 {
+		if info.isInvalid() {
 			if atEOF {
 				return i
 			}
@@ -465,7 +465,7 @@ func lastBoundary(fd *formInfo, b []byte) int {
 	if p == -1 {
 		return -1
 	}
-	if info.size == 0 { // ends with incomplete rune
+	if info.isInvalid() { // ends with incomplete rune
 		if p == 0 { // starts with incomplete rune
 			return -1
 		}
@@ -504,7 +504,7 @@ func lastBoundary(fd *formInfo, b []byte) int {
 func decomposeSegment(rb *reorderBuffer, sp int, atEOF bool) int {
 	// Force one character to be consumed.
 	info := rb.f.info(rb.src, sp)
-	if info.size == 0 {
+	if info.isInvalid() {
 		return 0
 	}
 	if s := rb.ss.next(info); s == ssStarter {
@@ -528,7 +528,7 @@ func decomposeSegment(rb *reorderBuffer, sp int, atEOF bool) int {
 			break
 		}
 		info = rb.f.info(rb.src, sp)
-		if info.size == 0 {
+		if info.isInvalid() {
 			if !atEOF {
 				return int(iShortSrc)
 			}