fix(docker): correct port mapping and improve container startup

- Fix port mapping from 5001:5001 to 5001:5000 to match internal application port
- Add entrypoint script for proper database initialization and seeding
- Set PORT environment variable to 5000 for consistency
- Update Dockerfile to use entrypoint script with proper line ending handling

calorie_tracker_app/entrypoint.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+# Exit immediately if a command exits with a non-zero status
+set -e
+
+# Initialize database
+echo "Initializing database..."
+flask init-db
+
+# Seed database
+echo "Seeding database..."
+flask seed-db
+
+# Start Gunicorn
+# Use PORT environment variable if set, otherwise default to 5000
+PORT=${PORT:-5000}
+echo "Starting Gunicorn on port $PORT..."
+exec gunicorn -w 4 -b 0.0.0.0:$PORT app:app