fix(context left after review): review footer context after /review (#5610)

## Summary
- show live review token usage while `/review` runs and restore the main
session indicator afterward
  - add regression coverage for the footer behavior

## Testing
  - just fmt
  - cargo test -p codex-tui

Fixes #5604

---------

Signed-off-by: Fahad <fahad@2doapp.com>

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

@@ -114,6 +114,11 @@ impl BottomPane {
         self.status.as_ref()
     }
 
+    #[cfg(test)]
+    pub(crate) fn context_window_percent(&self) -> Option<i64> {
+        self.context_window_percent
+    }
+
     fn active_view(&self) -> Option<&dyn BottomPaneView> {
         self.view_stack.last().map(std::convert::AsRef::as_ref)
     }