Make voxel collision queries generic over the voxel storage with a VoxelQuery trait

[0xbeefd1ed]

Summary

Parry's voxel collision algorithms were written directly against a concrete Voxels shape. Anyone with their own sparse voxel structure (a chunked grid, an octree, a VDB-style tree) had to copy it into a Voxels before they could get contacts, intersection tests, or shape-casts against it.

This PR introduces a VoxelQuery trait that abstracts the storage, and rewrites the voxel query functions to take any V: ?Sized + VoxelQuery instead of &Voxels. The existing Voxels shape implements the trait, so calls that pass a &Voxels keep working unchanged.

What changed

• VoxelQuery trait (src/shape/voxels/voxel_query.rs). Implementors provide voxel_size, domain, and voxels_in_range. Grid helpers (voxel_at_point, voxel_center, voxel_aabb, voxel_range_intersecting_local_aabb, align_aabb_to_grid, local_aabb, and the aabb-based iterators) have default implementations derived from those three.
• QueriedVoxel trait, the per-voxel view a storage hands out through the VoxelQuery::Voxel<'a> associated type. Views may borrow from the storage, so a sparse tree can compute voxel_state() lazily from leaf-local context. The cheap voxel_type() is what bulk iteration reads; the full voxel_state() is only requested for contact-candidate voxels.
• Generic query functions. contact_manifolds_voxels_{shape,ball,composite_shape,voxels}, intersection_test_{voxels_shape,shape_voxels}, cast_shapes_{voxels_shape,shape_voxels}, cast_shapes_nonlinear_{voxels_shape,shape_voxels}, and MassProperties::from_voxels now take a VoxelQuery storage. The 2D and 3D to_outline, to_polyline, and to_trimesh conversions read through QueriedVoxel as well.
• Voxels implements VoxelQuery with VoxelData as its view, and VoxelData implements QueriedVoxel.
• VoxelState::with_filled_neighbors(AxisMask) builds a filled voxel's state from the set of its filled axis-aligned neighbors, for storages that only track occupancy.
• Default for VoxelType (Empty) and VoxelState (EMPTY).
• contact_manifolds_voxels_ball is now re-exported from parry::query alongside the other voxel manifold functions.

Test plan

• cargo test -p parry2d and cargo test -p parry3d pass on all four crate variants.
• cargo test --doc passes, including the new VoxelState::with_filled_neighbors example.
• RUSTDOCFLAGS="-D warnings" cargo doc --workspace --no-deps passes.
• Existing voxel regression tests (issue_345, issue_373, issue_382, issue_404) still pass against the Voxels implementation of the trait.