Add public API for aligned memory allocation, exposing the existing
mem_allocator_malloc_aligned infrastructure through wasm_export.h.
- Add wasm_runtime_aligned_alloc() API declaration with documentation
- Implement internal helper wasm_runtime_aligned_alloc_internal()
- Add public function with size/alignment validation
- POOL mode only, returns NULL for other memory modes
- Follows wasm_runtime_malloc() patterns for consistency
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
