feat: add ShapeTypeStaticChainLoop and ShapeTypeEdge collider shapes

[AnthonyWadham]

TL;DR

Added two new collider shape types: ShapeTypeStaticChainLoop for closed chain boundaries and ShapeTypeEdge for single line segments.

What changed?

• Added ShapeTypeStaticChainLoop constant that creates closed chain loops where the last vertex automatically connects to the first
• Added ShapeTypeEdge constant for single line segments using exactly 2 points, providing a lighter alternative to 2-point chains
• Added EdgeVertices [2]Vec2 field to ColliderShape struct for edge geometry data
• Updated validation logic to include the new shape types and validate EdgeVertices
• Implemented buildChainLoopShape() and buildEdgeShape() functions to create the corresponding Box2D shapes
• Enhanced body type validation to prevent dynamic bodies from using chain loop or edge shapes (they require zero mass)
• Updated deep copy and equality comparison functions to handle the new EdgeVertices field
• Exported the new shape type constants in the public plugin interface

Why make this change?

This extends the physics2D plugin's shape capabilities to support more diverse collision geometry. Chain loops provide an efficient way to create sealed boundaries without manually connecting the last point to the first, while edge shapes offer a performance-optimized option for simple line segments compared to using chains with only two points.

[AnthonyWadham]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: physics2d Cardinal integration tests #881
• refactor: merge Rigidbody2D and Collider2D into PhysicsBody2D #886
• feat: add ShapeTypeStaticChainLoop and ShapeTypeEdge collider shapes #883 👈 (View in Graphite)
• feat: add Box2D physics2d plugin with CGO #880 : 1 other dependent PR (#882 )
• main

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