Custom validators for shape props

Demonstrates using custom validators with .check() and .refine() methods to add validation constraints to shape props.

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This example shows how to create custom validators for shape properties using @tldraw/validate. It demonstrates:

• Chaining .check() calls to add validation constraints without transforming values
• Using .refine() to validate and transform values

The example creates a custom shape with two validated properties:

1. Percentage - Chains multiple .check() calls to validate that the value is between 0 and 100. Invalid values throw an error.
2. Rating - Uses .refine() to clamp values to the 1-5 range. Invalid values are transformed rather than rejected.

When the example loads, it demonstrates both behaviors: attempting to create a shape with percentage=150 throws an error, while creating a shape with rating=10 succeeds but the value is clamped to 5.