fix: taking plan type from usage endpoint instead of thru auth token (#7610)

pull plan type from the usage endpoint, persist it in session state /
tui state, and propagate through rate limit snapshots

codex-rs/app-server/src/bespoke_event_handling.rs

@@ -1499,6 +1499,7 @@ mod tests {
                 unlimited: false,
                 balance: Some("5".to_string()),
             }),
+            plan_type: None,
         };
 
         handle_token_count_event(