fix: align Android bundles for 16 KB page devices

[leehack]

Summary

• enable Android flexible page-size support in the common CMake preset and the scripted OpenCL loader build path so all packaged Android .so files are linked for 16 KB-compatible devices
• pin the Android release workflow to NDK 28.2.13676358 and export ANDROID_NDK_HOME explicitly so CI produces reproducible page-size-compatible artifacts
• validate staged Android release payloads with llvm-readelf -lW and fail the workflow if any shared library still ships with LOAD alignment below 0x4000

Validation

• python3 -m py_compile tools/build.py
• python3 - <<'PY' ... json.loads(Path('CMakePresets.json').read_text()) ... PY
• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/native_release.yml")'
• ANDROID_NDK_HOME="/Users/jhin.lee/Library/Android/sdk/ndk/28.2.13676358" python3 tools/build.py android --clean --abi arm64-v8a --backend full --jobs 4
• verified every built Android arm64 .so in bin/android/arm64 reports 0x4000 LOAD alignment via llvm-readelf -lW