fix(types): add angle option to ArcOptions

[TheMankel]

Summary

The angle option is supported at runtime for arc elements, but is missing from the ArcOptions TypeScript definition.

The option is already documented in the Arc Configuration.

Example

The following Polar Area configuration works at runtime, but TypeScript reports an error on angle because the property is missing from ArcOptions:

const angles = [60, 120, 180];
const config = {
  type: "polarArea",
  data: { labels: ["A", "B", "C"], datasets: [{ data: [1, 1, 1] }] },
  options: {
    elements: {
      arc: {
        angle: (context) => angles[context.dataIndex],
      },
    },
  },
};

This change adds the missing angle property to ArcOptions so the existing runtime functionality can be used without a TypeScript error.

Note

If there is a reason why angle is intentionally not part of ArcOptions, please let me know.