fix: Apply ARM64 compatibility fix directly to Faiss submodule

- Modify faiss/impl/pq.cpp to use x86-specific preprocessor conditions
- Remove patch file approach in favor of direct submodule modification
- Update CMakeLists.txt to reflect the submodule changes
- Fixes ARM64 Linux compilation by preventing x86 SIMD header inclusion

This resolves the "xmmintrin.h: No such file or directory" error
when building ARM64 Linux wheels for Docker compatibility.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/leann-backend-hnsw/CMakeLists.txt

@@ -60,6 +60,9 @@ if(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|arm64")
     # Use SVE optimization level for ARM64 (as seen in Faiss conda build)
     set(FAISS_OPT_LEVEL "sve" CACHE STRING "" FORCE)
     message(STATUS "Setting FAISS_OPT_LEVEL to 'sve' for ARM64")
+
+    # ARM64 compatibility: Faiss submodule has been modified to fix x86 header inclusion
+    message(STATUS "Using ARM64-compatible Faiss submodule")
 endif()
 
 # Additional optimization options from INSTALL.md