Extend jobs to run android and report binary sizes

[k-wasniowski]

Add Android CI/CD builds and binary size reporting

Summary

Extends the GitHub Actions CI/CD pipeline to cross-compile for Android and report binary sizes on every PR.

What Changed

Android build job (android-build)

• New matrix job cross-compiling sframe for Android using the NDK toolchain
• Targets 3 ABIs: arm64-v8a, armeabi-v7a, x86_64 (API level 24+)
• Uses vcpkg with VCPKG_CHAINLOAD_TOOLCHAIN_FILE to layer the Android NDK toolchain under vcpkg's package management
• Tests all 3 crypto backends (OPENSSL_1_1, OPENSSL_3, BORINGSSL) and both NO_ALLOC modes
• Installs nasm and ninja-build dependencies (required by BoringSSL and the Ninja generator)
• Runs in parallel with the existing desktop builds — no sequential dependency

Binary size reporting (size-report)

• Both desktop-build and android-build jobs now record the built library size after each build
• Each matrix combination uploads a uniquely-named CSV artifact to avoid merge collisions
• A new size-report job runs after all builds complete (PR only), collecting all size artifacts and posting a Markdown summary table as a sticky PR comment via marocchino/sticky-pull-request-comment

Job renaming

• build → desktop-build for clarity alongside the new android-build job

New CI jobs

Job	Runs on	Purpose
desktop-build	windows/ubuntu/macos	Existing desktop builds + tests (renamed)
android-build	ubuntu	Cross-compile for Android NDK targets
size-report	ubuntu (PR only)	Aggregate and post binary size table

Matrix coverage

Desktop (existing)

• 3 OS × 3 crypto × 2 alloc = 18 combinations

Android (new)

• 3 ABI × 3 crypto × 2 alloc = 18 combinations