bug: _GENAI_CLIENT singleton not thread-safe on cold start

[QuantumByte-01]

Problem

Two concurrent requests hitting a cold start can both see _GENAI_CLIENT is None and both initialize it:

_GENAI_CLIENT = None

def _get_genai_client():
    global _GENAI_CLIENT
    if _GENAI_CLIENT is None:   # race condition here
        _GENAI_CLIENT = genai.Client(...)
    return _GENAI_CLIENT

Fix

Use asyncio.Lock or initialize the client eagerly at module load time instead of lazily.

[Nabhye]

Hi, I’d like to work on this issue.
I plan to fix it using asyncio.Lock with double-checked locking to ensure thread-safe initialization.
Please let me know if this approach works.