Refactor Android build workflow: explicit SDK setup, unified /opt/android-deps prefix

[Copilot]

The build workflow lacked an explicit Android SDK/NDK download step and cross-compiled libraries were scattered across /tmp with library-specific paths. This refactor structures each Android build job into four clear phases: SDK download → cross-compile deps → build wheels → upload.

Changes

Android SDK download step (wheels.yml)

Added to all three build jobs (build_dependency_packages, build_independent_packages, build_dependent_packages). Runs only on Linux (Android targets):

- name: Download Android SDK
  if: steps.check-skip.outputs.skip != 'true' && runner.os == 'Linux'
  run: |
    sudo apt-get install -y unzip cmake ninja-build gcc wget curl autoconf automake libtool pkg-config meson
    wget -O ndk.zip https://dl.google.com/android/repository/android-ndk-r29-linux.zip
    sudo unzip ndk.zip -d /opt/Android/Sdk/ndk
    ...
    echo "ANDROID_NDK_ROOT=/opt/Android/Sdk/ndk/android-ndk-r29" >> "$GITHUB_ENV"

Unified cross-compile prefix for Android deps

All three library build scripts now install to /opt/android-deps/${ANDROID_ABI} instead of per-library paths under /tmp:

• build_libjpeg.sh: /tmp/libjpeg-install-${ABI} → /opt/android-deps/${ABI}
• build_zlib.sh: /tmp/zlib-install-${ABI} → /opt/android-deps/${ABI}
• build_libtiff.sh: /tmp/libtiff-install-${ABI} → /opt/android-deps/${ABI}

Updated library discovery

• cross_compile_libs_detect.patch: replaced three separate /tmp/*-install-*/include globs with a single glob('/opt/android-deps/*/include') that covers all libs per ABI in one pass
• setup_cross_compile_env.sh: added /opt/android-deps/* as a primary search location

cibuildwheel env passthrough

CIBW_ENVIRONMENT_PASS_LINUX in all three jobs now includes ANDROID_SDK_ROOT ANDROID_HOME ANDROID_NDK_ROOT so the SDK paths are available inside the cibuildwheel build environment.

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