feat: Add Docker support for MERN template

[amanvatss]

Hi @JoeCelaster, this PR adds full Docker support for the MERN template, allowing developers to get the entire application running with a single command.

---

Before This PR

To run the project, a developer had to:

1. Manually install Node.js on their machine.
2. Manually install and run a MongoDB database.
3. Open a terminal to install dependencies and run the backend server.
4. Open a second terminal to install dependencies and run the frontend client.

---

After This PR (Proof of Work)

With these changes, a developer only needs to have Docker installed and run one command: docker-compose up.

This automatically builds, installs, and runs the frontend, backend, and database in a containerized environment.

Here is a screenshot of the final result, showing the application running successfully in the browser:

---

Files Added

• templates/mern/javascript/server/Dockerfile: A recipe to containerize the backend server.
• templates/mern/javascript/client/Dockerfile: A recipe to containerize the frontend client.
• templates/mern/javascript/docker-compose.yml: An orchestration file to manage and connect the client, server, and database containers.
• templates/mern/javascript/client/package.json: Updated the dev script to vite --host to allow external connections.

This feature significantly improves the developer experience and aligns with the project's goal of faster setups.

Closes #103

[Abdulk077]

i think we need a little improvement here you mention both server and client in same image i think best practice should be creating image for server and client separate is better

[amanvatss]

Hi @Abdulk077, thanks for the feedback! You are absolutely right that separate images for the server and client is the best practice.

That is the approach I have taken in this pull request. If you look at the files, you'll see:

• templates/mern/javascript/server/Dockerfile builds the image for the backend.
• templates/mern/javascript/client/Dockerfile builds the image for the frontend.
• templates/mern/javascript/docker-compose.yml then starts these two separate services (client and server) along with the database.

I believe this follows the best practice you mentioned. Please let me know if you see anything I could improve in the implementation. Thanks!

[Abdulk077]

one thing you should add the a non-root user for better security for an frontend app , one thing in production uses separate compose file for scaling purpose that's what all I said .

[Abdulk077]

Give me an opportunity for dockerise
Another mern app of this template for dev , then for production level later.