Add Android debug CI checks

[poulcarlsen53]

What changed

This adds a small Android CI workflow for regular PR and main-branch checks:

• sets up Java 21, matching the checked-in Gradle daemon criteria
• installs Android 36 build tools and the app NDK version
• runs unit tests and assembles the debug APK
• fixes the generated instrumentation test package/assertion so connected debug tests do not fail immediately
• writes scan resolver handoff files with \n explicitly instead of platform-specific newlines

Why

Before this, the only pull request workflow guarded the StormDNS upstream boundary. Gradle test or packaging regressions could merge without a signal. While testing this locally on Windows, the scan resolver test also exposed a newline portability issue, so this PR fixes that instead of weakening the test.

I intentionally left lintDebug out of this first workflow because the current tree already has lint errors. Adding lint here would make the new required check fail before this PR changes anything meaningful about lint.

Verification

• ./gradlew :app:testDebugUnitTest --no-daemon
• ./gradlew :app:compileDebugAndroidTestKotlin --no-daemon
• ./gradlew :app:testDebugUnitTest :app:assembleDebug --no-daemon --stacktrace

Note: ./gradlew :app:lintDebug :app:assembleDebug --no-daemon currently fails on existing Compose lint errors such as LocalContextGetResourceValueCall in WhiteDnsScreen.kt.