chore: import Local-Cursor v1.1.8 source snapshot

Includes the current working directory changes. Historical commits and release binaries are excluded to limit Gitea storage.
Source base: d7515973fbfd6dd2001fa156c483455b8081c7cb

internal/backend/forwarder/process_exists_unix.go

@@ -0,0 +1,18 @@
+//go:build !windows
+
+package forwarder
+
+import (
+	"errors"
+	"os"
+	"syscall"
+)
+
+func processExists(pid int) bool {
+	process, err := os.FindProcess(pid)
+	if err != nil || process == nil {
+		return false
+	}
+	err = process.Signal(syscall.Signal(0))
+	return err == nil || errors.Is(err, syscall.EPERM)
+}