fix(ci): standardize Android ARM release build

scripts/build_android.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Build the supported Android release APKs for SpotiFLAC Mobile.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
+OUTPUT_DIR="$PROJECT_DIR/build/app/outputs/flutter-apk"
+
+cd "$PROJECT_DIR"
+flutter build apk \
+  --release \
+  --split-per-abi \
+  --target-platform android-arm,android-arm64 \
+  "$@"
+
+for apk in app-armeabi-v7a-release.apk app-arm64-v8a-release.apk; do
+  if [[ ! -f "$OUTPUT_DIR/$apk" ]]; then
+    echo "Error: expected APK was not created: $OUTPUT_DIR/$apk" >&2
+    exit 1
+  fi
+done
+
+echo "Built Android release APKs in $OUTPUT_DIR"