Update: frontend polish with shadcn/ui, backend refactor, specs updates

Add librdkafka-dev for confluent-kafka build

Clean requirements.txt for FastAPI + PostgreSQL + Kafka/Dapr

Suppress pip root warning for Back4App deployment

Update root Dockerfile to Python 3.13 and remove duplicate backend/Dockerfile

Update Dockerfile with git and pip upgrade

Update Dockerfile for Back4App deployment

Merge branch 'main' of https://github.com/zahidaraees/hackathon-ii-phase-ii-Full-Stack-Web-Application

Remove .env.example to protect secrets

Delete .env.example

Updated Example .env file

Move Dockerfile to repo root for Back4App and update configs

Add Dockerfile for Back4App deployment

Add Dockerfile for Back4App deployment

Optimize requirements.txt for Railway deployment