chore: enhance Dockerfiles and package.json for improved build process

- Added ENV npm_config_ignore_scripts=true to frontend and backend Dockerfiles to skip scripts during npm install, optimizing build times.
- Introduced a postinstall script in package.json to ensure the build process for @mmapp/contracts runs after installation.

backend/Dockerfile

@@ -5,6 +5,7 @@ RUN apt-get update \
   && apt-get install -y --no-install-recommends python3 make g++ \
   && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
+ENV npm_config_ignore_scripts=true
 COPY package.json package-lock.json ./
 COPY packages/contracts/package.json packages/contracts/
 COPY backend/package.json backend/