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_solaris.go

@@ -629,7 +629,7 @@ func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 //sys	Kill(pid int, signum syscall.Signal) (err error)
 //sys	Lchown(path string, uid int, gid int) (err error)
 //sys	Link(path string, link string) (err error)
-//sys	Listen(s int, backlog int) (err error) = libsocket.__xnet_llisten
+//sys	Listen(s int, backlog int) (err error) = libsocket.__xnet_listen
 //sys	Lstat(path string, stat *Stat_t) (err error)
 //sys	Madvise(b []byte, advice int) (err error)
 //sys	Mkdir(path string, mode uint32) (err error)
@@ -1052,14 +1052,6 @@ func IoctlSetIntRetInt(fd int, req int, arg int) (int, error) {
 	return ioctlRet(fd, req, uintptr(arg))
 }
 
-func IoctlSetString(fd int, req int, val string) error {
-	bs := make([]byte, len(val)+1)
-	copy(bs[:len(bs)-1], val)
-	err := ioctlPtr(fd, req, unsafe.Pointer(&bs[0]))
-	runtime.KeepAlive(&bs[0])
-	return err
-}
-
 // Lifreq Helpers
 
 func (l *Lifreq) SetName(name string) error {
@@ -1102,3 +1094,90 @@ func (s *Strioctl) SetInt(i int) {
 func IoctlSetStrioctlRetInt(fd int, req int, s *Strioctl) (int, error) {
 	return ioctlPtrRet(fd, req, unsafe.Pointer(s))
 }
+
+// Ucred Helpers
+// See ucred(3c) and getpeerucred(3c)
+
+//sys	getpeerucred(fd uintptr, ucred *uintptr) (err error)
+//sys	ucredFree(ucred uintptr) = ucred_free
+//sys	ucredGet(pid int) (ucred uintptr, err error) = ucred_get
+//sys	ucredGeteuid(ucred uintptr) (uid int) = ucred_geteuid
+//sys	ucredGetegid(ucred uintptr) (gid int) = ucred_getegid
+//sys	ucredGetruid(ucred uintptr) (uid int) = ucred_getruid
+//sys	ucredGetrgid(ucred uintptr) (gid int) = ucred_getrgid
+//sys	ucredGetsuid(ucred uintptr) (uid int) = ucred_getsuid
+//sys	ucredGetsgid(ucred uintptr) (gid int) = ucred_getsgid
+//sys	ucredGetpid(ucred uintptr) (pid int) = ucred_getpid
+
+// Ucred is an opaque struct that holds user credentials.
+type Ucred struct {
+	ucred uintptr
+}
+
+// We need to ensure that ucredFree is called on the underlying ucred
+// when the Ucred is garbage collected.
+func ucredFinalizer(u *Ucred) {
+	ucredFree(u.ucred)
+}
+
+func GetPeerUcred(fd uintptr) (*Ucred, error) {
+	var ucred uintptr
+	err := getpeerucred(fd, &ucred)
+	if err != nil {
+		return nil, err
+	}
+	result := &Ucred{
+		ucred: ucred,
+	}
+	// set the finalizer on the result so that the ucred will be freed
+	runtime.SetFinalizer(result, ucredFinalizer)
+	return result, nil
+}
+
+func UcredGet(pid int) (*Ucred, error) {
+	ucred, err := ucredGet(pid)
+	if err != nil {
+		return nil, err
+	}
+	result := &Ucred{
+		ucred: ucred,
+	}
+	// set the finalizer on the result so that the ucred will be freed
+	runtime.SetFinalizer(result, ucredFinalizer)
+	return result, nil
+}
+
+func (u *Ucred) Geteuid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGeteuid(u.ucred)
+}
+
+func (u *Ucred) Getruid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetruid(u.ucred)
+}
+
+func (u *Ucred) Getsuid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetsuid(u.ucred)
+}
+
+func (u *Ucred) Getegid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetegid(u.ucred)
+}
+
+func (u *Ucred) Getrgid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetrgid(u.ucred)
+}
+
+func (u *Ucred) Getsgid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetsgid(u.ucred)
+}
+
+func (u *Ucred) Getpid() int {
+	defer runtime.KeepAlive(u)
+	return ucredGetpid(u.ucred)
+}