Fix Android CI, local build, and debug libgit2 runtime

[Kibnet]

Summary

• fix Android CI and local native dependency build flow, including submodule gitdir detection, repo-local NuGet packaging, and Android SDK alignment
• fix Windows-host OpenSSL relink for Android so Debug APK no longer carries a broken libssl.so.3 that causes System.DllNotFoundException: "git2-3f4182d"
• bump custom LibGit2Sharp.NativeBinaries to 2.0.324-android.5 and add regression coverage for the Android build scripts

Validation

• pwsh -File scripts/test-android-build-scripts.ps1
• dotnet restore src/Unlimotion.Android/Unlimotion.Android.csproj --configfile src/nuget.config
• dotnet build src/Unlimotion.Android/Unlimotion.Android.csproj -c Release -t:Package
• dotnet build src/Unlimotion.Android/Unlimotion.Android.csproj -c Debug -t:Package --no-restore -m:1 -nr:false -p:RuntimeIdentifier=android-arm64

Notes

• The latest Debug native fix was validated by inspecting the rebuilt ARM64 APK and native libraries.
• A fresh adb runtime smoke test was not rerun at PR time because no Android device was connected.