Fix Android emulation and runtime errors for both apps

- Add emulator management scripts (start/stop/status) with logging to /tmp
- Fix AVD config: enable GPU acceleration, increase RAM to 4096M
- Update babel-preset-expo 9.3.2 -> 55.0.8 to fix RN 0.83 private methods
  support without breaking polyfills
- Add Android package name to expo app.json
- Fix Flutter startup crash: call WidgetsFlutterBinding.ensureInitialized
  before accessing platform channels in db init

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/emu-stop.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# Stop Android emulator cleanly
+set -euo pipefail
+
+export ANDROID_HOME="$HOME/Android/Sdk"
+export PATH="$ANDROID_HOME/emulator:$ANDROID_HOME/platform-tools:$PATH"
+
+BOOT_LOG="/tmp/emulator-boot.log"
+
+echo "[$(date)] Stopping emulator..." | tee -a "$BOOT_LOG"
+
+if adb devices 2>/dev/null | grep -q "emulator"; then
+    adb emu kill 2>/dev/null || true
+    sleep 2
+fi
+
+pkill -f "qemu-system-x86_64" 2>/dev/null || true
+
+echo "[$(date)] Emulator stopped." | tee -a "$BOOT_LOG"