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.

android/README.md

@@ -0,0 +1,43 @@
+# Deck in a Dash — Android app
+
+A standalone Android app showing the same daily tarot (Celtic Cross) +
+astrology reading as the Pebble watch app (`../watch/`), with a burger
+menu leading to a config page. Independent of the watch app - neither
+requires the other to be installed. See the root
+[`CLAUDE.md`](../CLAUDE.md)'s "Android app" section for the full
+architecture (JNI-linked engine/interpreter, JSON bridge schema,
+WorkManager notification, card art pipeline).
+
+## Building
+
+Requires:
+
+- A JDK (17+; the project's own `compileOptions`/toolchain target Java
+  17). `JAVA_HOME` should point at it, or a `java` matching that version
+  must be first on `PATH`.
+- The Android SDK, with `ANDROID_HOME` (or `ANDROID_SDK_ROOT`) set -
+  needs at minimum `platforms;android-36`, `build-tools;36.0.0`,
+  `ndk;30.0.14904198`, and `cmake;3.22.1` installed (see
+  `app/build.gradle.kts`'s `compileSdk`/`ndkVersion` and
+  `app/src/main/jni/CMakeLists.txt`'s `cmake_minimum_required` for the
+  exact versions this project pins - `../build-image/Dockerfile`
+  installs the same ones for CI).
+- `ANDROID_NDK_HOME` set to that installed NDK's directory.
+- Python 3 + Pillow (`pip install Pillow`) - needed by
+  `scripts/gen_card_images.py`/`gen_launcher_icon.py`, which Gradle's
+  `preBuild` task runs automatically (see `app/build.gradle.kts`).
+
+```bash
+./gradlew assembleDebug   # -> app/build/outputs/apk/debug/app-debug.apk
+```
+
+Or, from the repo root: `make android`, which wraps the above and
+copies the APK into `dist/deck-in-a-dash-<version>.pbw`'s sibling,
+`dist/deck-in-a-dash-<version>.apk` (same version resolution as `make
+package`/`make watchapp` - see the root `Makefile`).
+
+The Gradle wrapper (`./gradlew`) resolves its own pinned Gradle version
+on first run - no separate Gradle install is needed.
+
+Ships the Android auto-generated debug keystore, not a release-signed
+build - see the root `CLAUDE.md`'s Android section for why.