Yifei/update llamacpp

[xsxszab]

Description

This pull request updates the Nexa SDK to integrate the latest changes from the Nexa fork of llama.cpp.

Upgrade Workflow

1. Done: Updated the Nexa fork of llama.cpp in NexaAI/llama.cpp, tracking branch: yifei/sync_upstream.
2. Done: Updated the Nexa SDK’s llama.cpp dependency to track yifei/sync_upstream and adjusted the SDK’s Python bindings accordingly.
3. Done: Updated all SDK components (e.g., OuteTTS) that depend on the llama.cpp Python bindings.
4. Done: Test everything, no errors encountered locally so far.
5. Done: Merge yifei/sync_upstream into main in NexaAI/llama.cpp and update the SDK to track the main branch.