Show token used when context window is unknown (#7497)

- Show context window usage in tokens instead of percentage when the
window length is unknown.

codex-rs/tui/src/status/mod.rs

@@ -5,6 +5,7 @@ mod helpers;
 mod rate_limits;
 
 pub(crate) use card::new_status_output;
+pub(crate) use helpers::format_tokens_compact;
 pub(crate) use rate_limits::RateLimitSnapshotDisplay;
 pub(crate) use rate_limits::rate_limit_snapshot_display;