Fix ground grid and generate infinite

[qianhexing]

Fix the ground grid effect to correctly display an infinite grid with proper line blending and transparency.

The previous implementation suffered from incorrect transparency calculations in gridLine and axisLine functions, which caused lines to render improperly. Additionally, the blending logic for minor, major, and axis lines did not correctly prioritize and combine the different grid components, leading to visual errors. This PR addresses these issues by correcting the transparency calculations and implementing a robust blending system that ensures higher-priority lines (like axes) correctly overlay lower-priority lines, resulting in a visually accurate and infinite ground grid.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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