[Bug Fixes]
1. Fixed a number of bugs.
[Content Improvements]
1. The upgrade experience for defense towers and city buildings has been improved.
2. Survivor dispatch has been adjusted: total survivor count has been reduced while increasing individual impact, and daytime dispatch is now required less frequently.
3. The Survivor Rescue Station has been added: it consumes manpower to search the block for survivors, and spending supplies can boost its efficiency.
4. Level 2 has been partially redesigned: a new area is now accessible, and the evacuation route has been repositioned to intensify defensive gameplay.
5. Volume controls for background music and sound effects have been added.
6. The selection of starting protagonists has been modified.
7. The Machine Gun Tower has been temporarily disabled.