- Removed the `signalChildWindowReady` function and replaced it with a loading shell in `ChildWindowRouter` to provide a better user experience during loading.
- Updated `FolderDialog` to prevent multiple submissions when pressing Enter and clicking Save simultaneously.
- Enhanced file handling in `FileDocumentEditor` and related components by adding `contentHash` and `mtimeNanos` properties for better file state management.
- Added tests for new functionality in `FolderDialog` and `FileDocumentEditor` to ensure reliability.
- Introduced `AlternateScreenStateTracker` and `Dec2026FrameGate` for improved terminal handling and performance metrics.