feat: add zero-allocation scalar getters/setters for RigidBody, Collider, and KinematicCharacterController

[GbGr]

Summary

Add scalar component getters and setters that return/accept individual f32→number values, bypassing all intermediate struct creation, WASM heap allocation, and JS wrapper object overhead.

Motivation

Every call to RigidBody.translation(), .rotation(), .linvel(), etc. currently creates multiple short-lived allocations:

1. Rust allocates a RawVector/RawRotation struct on the WASM heap (Box::new)
2. wasm-bindgen wraps the WASM pointer in a JS object (Object.create + FinalizationRegistry)
3. VectorOps.fromRaw() reads .x/.y via WASM getter calls, creates a new Vector2/Vector3/Quaternion, calls raw.free()

For game engines doing syncDynamicFromRapier with hundreds of entities at 60+ ticks/sec (with rollback resimulation multiplying that), this creates tens of thousands of short-lived allocations per second — unnecessary GC pressure.

The new scalar methods return primitives directly through the WASM stack, eliminating all allocations.

Per-call savings (getter)

	Old path	New path
WASM boundary crossings	4	1
WASM heap allocs	1	0
JS object allocs	2	0
WASM free calls	1	0

Changes

Rust (src/)

Getters (return f32, zero-alloc):

• RawRigidBodySet: rbTranslationX/Y(/Z), rbRotationAngle (2D), rbRotationX/Y/Z/W (3D), rbLinvelX/Y(/Z)
• RawColliderSet: coTranslationX/Y(/Z), coRotationAngle (2D), coRotationX/Y/Z/W (3D)
• RawKinematicCharacterController: computedMovementX/Y(/Z)

Setters (accept scalar args, avoid RawVector heap allocation):

• RawRigidBodySet: rbSetLinvelXY/XYZ, rbAddForceXY/XYZ, rbApplyImpulseXY/XYZ

TypeScript (src.ts/)

Corresponding methods on RigidBody, Collider, and KinematicCharacterController classes. All existing methods remain unchanged for backwards compatibility.

Tests

• rapier-compat/tests/ScalarGetters2d.test.ts
• rapier-compat/tests/ScalarGetters3d.test.ts

Verifies scalar getters match existing struct-returning methods, and scalar setters work correctly.

Backwards compatibility

Purely additive — no existing method signatures or return types were changed.