[FEATURE]: AI-powered "Chat with your Quiz" — ask follow-up questions on quiz content

### Feature and its Use Cases

## Problem
Currently, EduAid generates quizzes from content but provides no way
for users to interact with that content further. When a user gets a
question wrong or doesn't understand an answer, there is no way to
ask "why is this the correct answer?" or "explain this concept in
simpler terms". Users have to go back to the original source manually.

## Proposed Solution
Add a conversational AI layer on top of the generated quiz that allows
users to:

- Ask follow-up questions like "explain why option B is correct"
- Ask "give me an example of this concept"
- Ask "summarize this topic in simple terms"
- Chat directly with an uploaded PDF — ask questions about its content
beyond just the generated quiz

## How It Works

### Chat with Quiz
1. When a quiz is generated, the source content is stored as context
2. User can open a chat panel alongside the quiz
3. User asks a question — it gets matched against the source content
using semantic search (RAG)
4. A language model generates a grounded answer from the source material

### Chat with PDF
1. User uploads a PDF
2. PDF text is extracted and chunked
3. Chunks are embedded and stored in a FAISS vector index
4. User can ask any question about the PDF content
5. Relevant chunks are retrieved and passed to the LLM for a grounded answer

## Tech Stack Suggestion
- Python, FAISS, Sentence Transformers (all-MiniLM-L6-v2)
- LLM: Google Gemini API or local open-source model
- Frontend: existing React/JS chat UI pattern

## Why This Fits EduAid
EduAid's goal is to help students learn and retain information.
A chat interface transforms EduAid from a passive quiz tool into
an active learning companion — students don't just get tested,
they get to understand. This is a natural and powerful extension
of the existing quiz generation feature.

## Additional Notes
I have prior experience building a RAG pipeline from scratch
(DocuMind — PDF Q&A using FAISS + Gemini) and would love to
implement this feature. Happy to discuss the approach before
starting.

### Additional Context

_No response_

### Code of Conduct

- [x] I have joined the [Discord server](https://discord.gg/hjUhu33uAn) and will post updates there
- [x] I have searched existing issues to avoid duplicates