Store native libraries uncompressed and page-aligned - #111

android:extractNativeLibs="false" lets the platform mmap a native library
straight out of the APK/AAB instead of extracting a copy to app-private
storage at install time, but it only works if the library's zip entry is
stored (not deflated) and its data starts on a page boundary. Today every
entry except resources.arsc goes through the Deflated path with 4-byte
alignment, so that manifest flag isn't reachable.

This adds native-library detection matching both the APK layout
(lib/<abi>/*.so) and the AAB base-module layout (base/lib/<abi>/*.so,
kept generic instead of hardcoding known ABI names) and stores those
entries uncompressed with 16 KiB alignment — large enough to satisfy both
the traditional 4 KiB page size and the 16 KiB page size newer devices
require.

Non-native-library files are unaffected: resources.arsc keeps its
existing stored/4-byte-aligned handling, everything else still deflates.

Tested:

• 4 new unit tests in pack-zip (compression method, page alignment,
  path-matching edge cases for both APK and AAB layouts)
• Full workspace cargo test --workspace --lib --bins passes unmodified
  (the one pre-existing pack-api doctest failure is unrelated — it fails
  identically on main before this change)
• cargo +nightly fmt --check clean
• Verified against a real downstream consumer: repacked and re-signed with
  this branch, output still passes real apksigner verify (v2+v3),
  zipalign -c, and aapt2 dump packagename