Renamed chat_history.txt to chat_history.py and Updated routers/chat.py

[metadroix35]

Overview
This implementation adds persistent chat history to Pixly using ChromaDB. The chatbot will now remember previous conversations on a per-game basis, enabling context-aware responses and temporal queries.

📁 Files Changed/Added
New Files

backend/chat_history.py - Core chat history manager module

Handles storage, retrieval, and search
Manages per-game collections
Implements timestamp-based filtering

TL;DR - Chat History Implementation
What You Need
Files to Create/Modify:

CREATE: backend/chat_history.py (NEW FILE)
MODIFY: routers/chat.py (UPDATE EXISTING)

Dependencies:
✅ ZERO new dependencies! Uses existing ChromaDB.

[BrataBuilds]

Great work @metadroix35.