[GOOD FIRST ISSUE]: main.py too large and hard to maintain

### Context

The `main.py` file has grown to ~800 lines with multiple responsibilities.

### Problems
- Difficult to navigate and maintain
- Multiple unrelated classes in a single file
- Hard to test and extend

### Affected Files
- backend/Generator/main.py

### What Needs to Be Done

- Split large `main.py` into focused modules:
- question_generators.py
- answer_predictor.py
- utilities.py
- advanced_qa.py
- Updated `server.py` imports to use new structure
- Preserved all existing logic and functionality

### Resources

- [Contribution Guide - Start Here!](https://github.com/AOSSIE-Org/TODO/blob/main/CONTRIBUTING.md)
- [Discord Channel](https://discord.gg/hjUhu33uAn)

### Getting Started

- [x] I have joined the [Discord server](https://discord.gg/hjUhu33uAn) and will post updates there
- [x] I have read the [Contribution Guide](https://github.com/AOSSIE-Org/Template-Repo/blob/main/CONTRIBUTING.md)
- [x] I understand this issue is assigned on a first-come, first-served basis