Mirror JPH per-arch VECTOR alignment so 32-bit ARM builds

[Solidor777]

Problem

JoltC's LAYOUT_COMPATIBLE static_asserts in JoltCImpl/JoltC.cpp fail on 32-bit ARM targets (armv7 Android, armv7 Linux):

JoltC/Functions.h:55:1: error: static assertion failed due to requirement
    'alignof(JPC_Vec3) == alignof(JPH::Vec3)':
    align of JPC_Vec3 did not match align of JPH::Vec3

…and the same for JPC_Vec4, JPC_DVec3, JPC_Quat, JPC_Mat44, JPC_DMat44, JPC_RVec3, plus every higher-level struct that contains a vector field (JPC_ShapeCastSettings, JPC_CollideShapeSettings, JPC_BodyManager_DrawSettings, JPC_ContactPoints, JPC_ContactManifold).

Root cause

JoltPhysics/Jolt/Core/Core.h:180 defines:

#else  // 32-bit ARM
    #define JPH_VECTOR_ALIGNMENT 8 // 32-bit ARM does not support aligning on the stack on 16 byte boundaries
    #define JPH_DVECTOR_ALIGNMENT 8
#endif

JoltC's C-side typedefs in JoltC/Functions.h hardcode alignas(16) on JPC_Vec3 / Vec4 / Quat / Mat44 and alignas(32) on JPC_DVec3 / JPC_DMat44. On 32-bit ARM the C-side over-constrains relative to JPH; the static_assert fires.

Fix

Introduce JPC_VECTOR_ALIGNMENT / JPC_DVECTOR_ALIGNMENT macros at the top of JoltC/Functions.h mirroring the same per-arch logic JPH uses (x86 / x86_64 / aarch64 / WASM / E2K → 16/32; 32-bit ARM → 8/8; RISC-V splits on __riscv_xlen; PowerPC + LoongArch → 16/8). Replace the six load-bearing alignas(...) literals on the vector / matrix typedefs with the macros.

The macro values match the original on every 64-bit target, so this is a no-op except on the 32-bit ARM path that previously failed the build.

Verification

• x86_64-pc-windows-msvc host build: passes (no behaviour change).
• aarch64-linux-android cross-compile via cargo ndk r26d: passes.
• armv7-linux-androideabi cross-compile via cargo ndk r26d: passes (previously failed at LAYOUT_COMPATIBLE).

[Solidor777]

Verification breadcrumb: this fix is downstream-validated in CI on the Titan engine repo — titan-jolt-3d cross-compiles via cargo ndk against both aarch64-linux-android (no behaviour change vs. main) and armv7-linux-androideabi (previously failed at the LAYOUT_COMPATIBLE static_assert; now passes). Mobile CI matrix is now a hard PR gate on the Titan side.

Companion infrastructure PR (independent — ships the cargo-ndk integration on joltc-sys/build.rs): SecondHalfGames/jolt-rust#12.