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/scripts/gen_launcher_icon.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Generates the Android launcher icon from ../../res/logo.png.
+
+Produces:
+- mipmap-<density>/ic_launcher_foreground.png - the logo centered,
+  scaled to fit the adaptive-icon safe zone (66% of a 108dp canvas),
+  transparent background - paired at runtime with
+  @color/ic_launcher_background (see mipmap-anydpi-v26/ic_launcher.xml,
+  committed - a static reference, not generated) for API 26+.
+- mipmap-<density>/ic_launcher.png / ic_launcher_round.png - the same
+  logo flattened onto ic_launcher_background, for API <26 devices that
+  can't use the adaptive-icon XML at all.
+
+Generated output, not committed (see the repo's root .gitignore's
+/android/app/src/main/res/mipmap-* entries) - regenerate by running this
+script directly or via Gradle's generateLauncherIcon task (wired into
+app's preBuild, see ../app/build.gradle.kts). Requires Pillow, already
+part of build-image's toolchain.
+"""
+import os
+import sys
+
+from PIL import Image
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+LOGO_PATH = os.path.normpath(os.path.join(SCRIPT_DIR, "..", "..", "res", "logo.png"))
+RES_DIR = os.path.normpath(os.path.join(SCRIPT_DIR, "..", "app", "src", "main", "res"))
+
+BACKGROUND_RGBA = (27, 27, 47, 255)  # matches @color/ic_launcher_background
+
+# (density qualifier, adaptive-icon canvas px, legacy launcher px)
+DENSITIES = [
+    ("mdpi", 108, 48),
+    ("hdpi", 162, 72),
+    ("xhdpi", 216, 96),
+    ("xxhdpi", 324, 144),
+    ("xxxhdpi", 432, 192),
+]
+
+# Adaptive icons render only the inner ~66% "safe zone" reliably across
+# launchers that apply their own mask shape.
+SAFE_ZONE_RATIO = 0.66
+
+
+def resized_logo(logo, target_px):
+    ratio = target_px / max(logo.width, logo.height)
+    size = (round(logo.width * ratio), round(logo.height * ratio))
+    return logo.resize(size, Image.LANCZOS)
+
+
+def main():
+    logo = Image.open(LOGO_PATH).convert("RGBA")
+
+    for density, canvas_px, legacy_px in DENSITIES:
+        mipmap_dir = os.path.join(RES_DIR, f"mipmap-{density}")
+        os.makedirs(mipmap_dir, exist_ok=True)
+
+        # Adaptive-icon foreground: transparent canvas, logo scaled to the
+        # safe zone and centered.
+        foreground = Image.new("RGBA", (canvas_px, canvas_px), (0, 0, 0, 0))
+        fg_logo = resized_logo(logo, round(canvas_px * SAFE_ZONE_RATIO))
+        offset = ((canvas_px - fg_logo.width) // 2, (canvas_px - fg_logo.height) // 2)
+        foreground.paste(fg_logo, offset, fg_logo)
+        foreground.save(os.path.join(mipmap_dir, "ic_launcher_foreground.png"))
+
+        # Legacy (<API26) flattened fallback, same for round and square -
+        # launchers on those versions apply their own circular crop.
+        legacy = Image.new("RGBA", (legacy_px, legacy_px), BACKGROUND_RGBA)
+        legacy_logo = resized_logo(logo, round(legacy_px * SAFE_ZONE_RATIO))
+        legacy_offset = ((legacy_px - legacy_logo.width) // 2, (legacy_px - legacy_logo.height) // 2)
+        legacy.paste(legacy_logo, legacy_offset, legacy_logo)
+        legacy.convert("RGB").save(os.path.join(mipmap_dir, "ic_launcher.png"))
+        legacy.convert("RGB").save(os.path.join(mipmap_dir, "ic_launcher_round.png"))
+
+    print(f"wrote launcher icons for {len(DENSITIES)} densities to {RES_DIR}", file=sys.stderr)
+
+
+if __name__ == "__main__":
+    main()