[FEATURE]: Support Curved-Boundary Bar Charts with Dynamic Phase/Threshold Detection

What problem does this feature solve?

In physical domain modeling (such as thermodynamic P-T phase diagrams), industrial monitoring, and multi-parameter threshold analysis, data visualization often requires representing dynamic bar elements within a two-dimensional parameter space that interact with non-linear, curved decision boundaries.

Current Limitations:

1. Linear/Static Boundaries: Current shapes/shapes annotations in Plotly primarily target horizontal, vertical, or simple linear lines. Defining polynomial or spline-based curved boundary lines for dynamic spatial partitioning is not natively streamlined.
2. Complex Collision Logic: Calculating real-time intersections (collision detection) between moving/resizing bar vertices (e.g., X position = Pressure, Y height = Temperature) and curved thresholds to dynamically update bar styling (e.g., solid, liquid, gas, or custom status) is mathematically complex to implement manually on top of standard trace types.

Expected Experience:

We hope Plotly could consider providing native support or built-in mechanisms for curved decision boundaries. When a bar's position along the X-axis or height along the Y-axis changes, the chart can evaluate its top vertex against curved boundaries to trigger real-time state changes and dynamic styling.

🔗 Live Demo & Repository

• Live Demo: https://cnlnr.github.io/Curved-Boundary-Bar-Chart/
• GitHub Repository: https://github.com/cnlnr/Curved-Boundary-Bar-Chart

先查看链接的在线演示和仓库，然后审查 issue 中描述的 plotly.py 现有 shapes 和 annotations 支持。未指定具体文件或测试；请在实现之前定义曲线边界、碰撞检测和动态条形样式的 API 范围及验收标准。