example: Add area-chart, normal-dist2, 3d-plot examples#2

Last PR #1 I have forgot push the second commit. ## AreaChart ```bash cargo run --example area-chart ``` <img width="1039" alt="image" src="https://github.com/user-attachments/assets/9ca54ac5-5625-40c5-bbf3-60aac58e6cb2" /> ```bash cargo run --example normal-dist2 ``` ## Normal Dist 2 <img width="1136" alt="image" src="https://github.com/user-attachments/assets/7e9ec94e-a8f0-4e0d-97eb-9399f0145e39" /> ## 3D Plot ```bash cargo run --example 3d-plot ``` <img width="1136" alt="image" src="https://github.com/user-attachments/assets/03ea4351-d079-4372-af84-bd2429ccc098" /> ## 3D Plot2 ```bash cargo run --example 3d-plot2 ``` <img width="1136" alt="image" src="https://github.com/user-attachments/assets/ee96ec61-6417-455e-bfb3-14064095c814" /> And look the demo screenshot, the area chart border is not render correct.