Optimize Docker configuration and Nginx setup for production

[Yuvraj-025]

I have overhauled the frontend Docker and Nginx configurations to adhere to production best practices, address current build inefficiencies, and fix potential routing issues:

1. Drastically Improved Docker Build Speeds

Added .dockerignore: Included a .dockerignore file to block node_modules/, build/, .git/, and other local artifacts from being copied. This will significantly reduce the Docker context size and fix memory bloat during builds.
Enabled Layer Caching: Reordered the Dockerfile so package.json and package-lock.json are copied and installed (npm ci) before copying the rest of the source code. Now, Docker will cache our heavy NPM install layer during builds, saving massive amounts of time unless dependencies actually change.

2. Hardened Nginx Setup for Single Page Application (SPA)

Fixed Client-Side Routing: Injected the try_files $uri $uri/ /index.html; directive into nginx.conf. This is crucial for React Router; without it, navigating directly to nested routes (or refreshing them) would throw a 404 Not Found error.
Improved Client-Side Caching: Added cache expires max; directives for all static assets (js, css, png, SVG, etc.) to optimize browser load times on the client side.

3. Cleanup & Dependability

Mapped Nginx to serve out of its standard safe directory (/usr/share/nginx/html).
Ensured the container properly calls our npm run config && npm run build pipeline explicitly.
These changes make our Docker build pipeline far more efficient and guarantee our routing works seamlessly when the container is deployed.