Fix unprivileged mode command execution

- Apply environment variables to command
- Set stdin/stdout/stderr for proper I/O
- Add missing os import

Co-authored-by: f0ssel <[email protected]>

Author: blink-so[bot]

namespace/unprivileged.go

@@ -3,6 +3,7 @@ package namespace
 import (
 	"fmt"
 	"log/slog"
+	"os"
 	"os/exec"
 )
 
@@ -39,6 +40,10 @@ func (u *Unprivileged) Start() error {
 
 func (u *Unprivileged) Command(command []string) *exec.Cmd {
 	cmd := exec.Command(command[0], command[1:]...)
+	cmd.Env = u.commandEnv
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.Stdin = os.Stdin
 	return cmd
 }