fix(ls): force LC_TIME=C for locale-independent date parsing

The LS_DATE_RE regex expects English month names (Jan, Feb, etc.),
but ls -la output uses numeric months (5, 6, etc.) when the user's
locale sets LC_TIME to a non-English language.

This causes parse_ls_line() to fail on every line, making rtk ls
always return '(empty)' on such systems (e.g. Chinese locale).

Fix by setting LC_TIME=C before executing ls, ensuring the date
format is always 'May  3 12:23' regardless of system locale.

Fixes #(issue number if known)

Author: lakewaban

src/cmds/system/ls.rs

@@ -36,6 +36,9 @@ pub fn run(args: &[String], verbose: u8) -> Result<i32> {
 
     let mut cmd = resolved_command("ls");
     cmd.arg("-la");
+    // Force English date format so LS_DATE_RE can parse the output reliably,
+    // regardless of the user's locale/LC_TIME setting.
+    cmd.env("LC_TIME", "C");
     for flag in &flags {
         if flag.starts_with("--") {
             if *flag != "--all" {