add maximum size limit for texture dimensions and fix build error cau…

[weykon]

1.Add .gitkeep

• Add .gitkeep file to maintain assets/models directory structure
• Fix build error caused by missing models directory

Why

• Git doesn't track empty directories by default
• The models directory is required for the build process
• .gitkeep is a common convention to maintain empty directory structure

2. Fix texture size limit overflow

Changes

• Add size limit check for depth texture creation
• Limit texture dimensions to 8192x8192 using min() function
• Fix potential GPU validation error caused by oversized textures

Why

• Previous code allowed unlimited texture dimensions
• GPU has hardware limits for maximum texture size
• Caused validation error: "Dimension X value exceeds the limit of 8192"