⚡ Bolt: Prevent Event Loop Blocking with AsyncGroq

[Adityasingh-8858]

💡 What: Replaced the synchronous Groq client with AsyncGroq in the FastAPI backend (backend/main.py). The .create() calls for LLM completions in /ai-voice and /initiate-transfer endpoints are now explicitly awaited. Added a critical learning entry to .jules/bolt.md.

🎯 Why: Using a synchronous HTTP client for network I/O inside an asynchronous endpoint blocks the main asyncio event loop. While waiting for the LLM to respond, the application becomes completely unresponsive to other incoming requests, severely degrading scalability and concurrent user performance.

📊 Impact: Massive improvement in concurrent request handling. The application can now process other requests (like /health, socket connections, or other endpoints) while waiting for the LLM API to respond, turning a blocking O(1) concurrent capability into an asynchronous model bounded only by available worker threads and memory.

🔬 Measurement: This can be verified by observing application responsiveness during a long LLM generation under load. To verify the code correctness, the standard backend test suite (python -m pytest) has been run and passes completely.

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PR created automatically by Jules for task 12592981905090610849 started by @Deepaksingh7238

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