chore: modernize CI and update Go toolchain

- Bump Go from 1.19 to 1.26 and update all dependencies
- Rewrite CI workflow with matrix strategy (Linux, macOS, Windows)
- Update GitHub Actions to current versions (checkout@v4, setup-go@v5)
- Update CodeQL actions from v1 to v3
- Fix cross-platform bug in mock/path.go (path.Join -> filepath.Join)
- Clean up dependabot config (weekly schedule, remove stale ignore)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/golang.org/x/sys/unix/syscall_darwin.go

@@ -402,6 +402,18 @@ func IoctlSetIfreqMTU(fd int, ifreq *IfreqMTU) error {
 	return ioctlPtr(fd, SIOCSIFMTU, unsafe.Pointer(ifreq))
 }
 
+//sys	renamexNp(from string, to string, flag uint32) (err error)
+
+func RenamexNp(from string, to string, flag uint32) (err error) {
+	return renamexNp(from, to, flag)
+}
+
+//sys	renameatxNp(fromfd int, from string, tofd int, to string, flag uint32) (err error)
+
+func RenameatxNp(fromfd int, from string, tofd int, to string, flag uint32) (err error) {
+	return renameatxNp(fromfd, from, tofd, to, flag)
+}
+
 //sys	sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) = SYS_SYSCTL
 
 func Uname(uname *Utsname) error {
@@ -542,6 +554,144 @@ func SysctlKinfoProcSlice(name string, args ...int) ([]KinfoProc, error) {
 	}
 }
 
+//sys	pthread_chdir_np(path string) (err error)
+
+func PthreadChdir(path string) (err error) {
+	return pthread_chdir_np(path)
+}
+
+//sys	pthread_fchdir_np(fd int) (err error)
+
+func PthreadFchdir(fd int) (err error) {
+	return pthread_fchdir_np(fd)
+}
+
+// Connectx calls connectx(2) to initiate a connection on a socket.
+//
+// srcIf, srcAddr, and dstAddr are filled into a [SaEndpoints] struct and passed as the endpoints argument.
+//
+//   - srcIf is the optional source interface index. 0 means unspecified.
+//   - srcAddr is the optional source address. nil means unspecified.
+//   - dstAddr is the destination address.
+//
+// On success, Connectx returns the number of bytes enqueued for transmission.
+func Connectx(fd int, srcIf uint32, srcAddr, dstAddr Sockaddr, associd SaeAssocID, flags uint32, iov []Iovec, connid *SaeConnID) (n uintptr, err error) {
+	endpoints := SaEndpoints{
+		Srcif: srcIf,
+	}
+
+	if srcAddr != nil {
+		addrp, addrlen, err := srcAddr.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+		endpoints.Srcaddr = (*RawSockaddr)(addrp)
+		endpoints.Srcaddrlen = uint32(addrlen)
+	}
+
+	if dstAddr != nil {
+		addrp, addrlen, err := dstAddr.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+		endpoints.Dstaddr = (*RawSockaddr)(addrp)
+		endpoints.Dstaddrlen = uint32(addrlen)
+	}
+
+	err = connectx(fd, &endpoints, associd, flags, iov, &n, connid)
+	return
+}
+
+const minIovec = 8
+
+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
+}
+
+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
+}
+
+func writevRacedetect(iovecs []Iovec, n int) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := int(iovecs[i].Len)
+		if m > n {
+			m = n
+		}
+		n -= m
+		if m > 0 {
+			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+}
+
+func readvRacedetect(iovecs []Iovec, n int, err error) {
+	if !raceenabled {
+		return
+	}
+	for i := 0; n > 0 && i < len(iovecs); i++ {
+		m := int(iovecs[i].Len)
+		if m > n {
+			m = n
+		}
+		n -= m
+		if m > 0 {
+			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
+		}
+	}
+	if err == nil {
+		raceAcquire(unsafe.Pointer(&ioSync))
+	}
+}
+
+//sys	connectx(fd int, endpoints *SaEndpoints, associd SaeAssocID, flags uint32, iov []Iovec, n *uintptr, connid *SaeConnID) (err error)
 //sys	sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error)
 
 //sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)
@@ -644,3 +794,7 @@ func SysctlKinfoProcSlice(name string, args ...int) ([]KinfoProc, error) {
 //sys	write(fd int, p []byte) (n int, err error)
 //sys	mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
 //sys	munmap(addr uintptr, length uintptr) (err error)
+//sys	readv(fd int, iovecs []Iovec) (n int, err error)
+//sys	preadv(fd int, iovecs []Iovec, offset int64) (n int, err error)
+//sys	writev(fd int, iovecs []Iovec) (n int, err error)
+//sys	pwritev(fd int, iovecs []Iovec, offset int64) (n int, err error)