Integrate uv for Server and GPU Worker containers

[alicup29]

This pull request updates the webRTC_external service to use a Python base image, adds a pyproject.toml for dependency management, and improves the container startup process by using uv for running the server.

Notes:

• Switched the base image in webRTC_external/Dockerfile from python:3.9-slim to python:3.12-slim-trixie for an updated Python environment, and added copying of the uv binary from the Astral container for improved performance.
• Changed the container entrypoint to use uv run for starting server.py.
• Added a pyproject.toml with project metadata and explicit dependencies, enabling modern Python packaging and dependency management.
• Added a dependencies comment block at the top of server.py to document required packages, and cleaned up import statements for clarity and consistency. (Remove later, cannot run server script as uvx)