Add weather system, change characters, and modify character animations

1. Add a weather system with preset settings and customizable weather, sky, rain, snow, lightning, rainbow, aurora, and more. Over 200 parameters can be customized (for indoor rain obstruction, you need to add the "block rain" feature in the terrain and adjust the size to include the entire house).
2. Replaced the character and corrected the character animation.
3. Partially optimized the texture.
4. Fixed some minor bugs.