style(update): remove unused sys import

Oops, sys is still used by sys.executable. Restored.

myclaude/commands/update.py

@@ -10,6 +10,7 @@ from rich.console import Console
 from myclaude.project_root import get_myclaude_project_root
 
 console = Console()
+stderr_console = Console(stderr=True)
 
 
 def _run_make_install(root: Path) -> int:
@@ -31,10 +32,9 @@ def update_cmd() -> None:
     root = get_myclaude_project_root()
     fallback = Path.home() / ".myclaude"
     if root == fallback:
-        console.print(
+        stderr_console.print(
             "[red]Not inside myclaude repo.[/red] Set [cyan]MYCLAUDE_PROJECT_ROOT[/cyan] "
             "or run from the clone.",
-            file=sys.stderr,
         )
         raise SystemExit(1)
 
@@ -49,6 +49,6 @@ def update_cmd() -> None:
         rc = _run_pip_editable(root)
 
     if rc != 0:
-        console.print("[red]Update failed.[/red]", file=sys.stderr)
+        stderr_console.print("[red]Update failed.[/red]")
         raise SystemExit(rc)
     console.print("[green]myclaude updated.[/green]")