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.

run-image.sh

@@ -1,12 +1,13 @@
 #!/usr/bin/env bash
-# Runs `make test package watchapp` inside the local build-image
+# Runs `make test package watchapp android` inside the local build-image
 # container, mirroring what the Gitea Actions build workflow does -
 # useful for testing build-image changes locally before pushing
 # anything to cr.ladkau.de.
 #
 # Usage: ./run-image.sh [VERSION]
 #   VERSION is passed through to `make` (see the Makefile's `package`/
-#   `watchapp` targets); omit it for their own git-tag-based default.
+#   `watchapp`/`android` targets); omit it for their own git-tag-based
+#   default.
 set -euo pipefail
 
 cd "$(dirname "${BASH_SOURCE[0]}")"
@@ -36,22 +37,28 @@ VERSION="${1:-${VERSION:-}}"
 
 # CI always starts from a fresh checkout, but this script bind-mounts the
 # live host repo — so build output left over from a previous local run
-# (build/, dist/, watch/build, and the generated watch resources below)
-# would make this run skip work a real fresh checkout wouldn't, silently
-# hiding bugs that only show up in CI. Wipe them first so every run
-# exercises a true from-scratch build, same as CI.
+# (build/, dist/, watch/build, the generated watch resources below, and
+# the Android app's own build/generated-resource dirs) would make this
+# run skip work a real fresh checkout wouldn't, silently hiding bugs that
+# only show up in CI. Wipe them first so every run exercises a true
+# from-scratch build, same as CI.
 echo "== Cleaning generated build artifacts for a fresh build =="
 rm -rf \
     "$ROOT/build" "$ROOT/dist" "$ROOT/watch/build" \
     "$ROOT/watch/resources/img" "$ROOT/watch/resources/app_icon.png" \
-    "$ROOT/watch/src/c/i18n_tables.auto.c"
+    "$ROOT/watch/src/c/i18n_tables.auto.c" \
+    "$ROOT/android/build" "$ROOT/android/app/build" "$ROOT/android/app/.cxx" \
+    "$ROOT/android/app/src/main/assets/i18n" "$ROOT/android/app/src/main/res/drawable-nodpi" \
+    "$ROOT/android/app/src/main/res"/mipmap-mdpi "$ROOT/android/app/src/main/res"/mipmap-hdpi \
+    "$ROOT/android/app/src/main/res"/mipmap-xhdpi "$ROOT/android/app/src/main/res"/mipmap-xxhdpi \
+    "$ROOT/android/app/src/main/res"/mipmap-xxxhdpi
 
-echo "== Running make test package watchapp inside $IMAGE =="
+echo "== Running make test package watchapp android inside $IMAGE =="
 # The container runs as root (needed for the toolchain baked into the
 # image), so anything it writes into this bind mount — dist/, build/,
-# watch/build, etc. — would otherwise come back owned by root, leaving
-# the host repo unusable without sudo. Chown everything back to the host
-# user on exit, whether the build succeeds or fails.
+# watch/build, android/.gradle, etc. — would otherwise come back owned
+# by root, leaving the host repo unusable without sudo. Chown everything
+# back to the host user on exit, whether the build succeeds or fails.
 docker run --rm \
     -v "$ROOT:/workspace" \
     -w /workspace \
@@ -62,7 +69,7 @@ docker run --rm \
     bash -c '
         git config --global --add safe.directory /workspace
         trap "chown -R \"$HOST_UID:$HOST_GID\" /workspace" EXIT
-        make test package watchapp
+        make test package watchapp android
     '
 
 echo "== Done — artifacts in dist/ =="