Add a standalone Android app with the same daily reading and config page

android/ links engine/src/ and interpreter/src/ via JNI/CMake (real
astronomy.c, not the watch's size-constrained substitute), rendering
through Jetpack Compose with a burger-menu config page mirroring
WatchConfig and a WorkManager-driven daily notification. Independent
of the watch app - neither requires the other.

build-image now bundles the Android SDK/NDK alongside the Pebble SDK
(VERSION bumped to 2), and .gitea/workflows/build.yml/Makefile/
run-image.sh build and publish the APK the same way as the CLI
tarball and .pbw.

.gitignore

@@ -13,6 +13,23 @@
 # added this .gitignore line for the git rm --cached that untracked it.
 /watch/.lock-waf_linux_build
 
+# Android app build output/local config and generated resources (card
+# art, launcher icon, synced i18n files - see android/app/build.gradle.kts's
+# generateCardArt/generateLauncherIcon/syncI18n tasks and their own
+# source scripts' doc comments).
+/android/local.properties
+/android/.gradle
+/android/build
+/android/app/build
+/android/app/.cxx
+/android/app/src/main/assets/i18n
+/android/app/src/main/res/drawable-nodpi
+/android/app/src/main/res/mipmap-mdpi
+/android/app/src/main/res/mipmap-hdpi
+/android/app/src/main/res/mipmap-xhdpi
+/android/app/src/main/res/mipmap-xxhdpi
+/android/app/src/main/res/mipmap-xxxhdpi
+
 # Durable backup of the same real birth data, outside dist/ so a dist/
 # wipe doesn't lose it — see the Makefile's `scripts` target. Never
 # commit this either.