Add initial project structure with Docker setup and frontend/backend files

backend/Dockerfile

@@ -0,0 +1,9 @@
+FROM python:3.9-slim
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+COPY . .
+ENV DATABASE_URL=postgresql://username:password@db/workout_buddy
+ENV JWT_SECRET_KEY=super-secret
+EXPOSE 5000
+CMD ["python", "app.py"]