feature: update system design and introduce easy to use decorator

[vcfgv]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces an agent system with a decorator-based approach for creating and managing agents. The system provides an easy-to-use @serve decorator that allows users to define agents with minimal boilerplate and automatic service management.

Key Changes

• Added agent type definitions and base classes for streaming agents
• Implemented a decorator system (@serve) that automatically wraps classes into agents with A2A SDK integration
• Created an agent registry for managing decorated agent classes
• Built connection management utilities for starting, stopping, and communicating with agents

Reviewed Changes

Copilot reviewed 11 out of 14 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
python/valuecell/utils/uuid.py	Utility for generating UUIDs with optional prefixes
python/valuecell/utils/port.py	Port management utility for finding available ports
python/valuecell/utils/__init__.py	Utils package exports
python/valuecell/core/agent/types.py	Base agent types and response models
python/valuecell/core/agent/registry.py	Agent registry for managing decorated agent classes
python/valuecell/core/agent/decorator.py	Core @serve decorator implementation with A2A integration
python/valuecell/core/agent/listener.py	HTTP notification listener for push notifications
python/valuecell/core/agent/client.py	Client for communicating with agents
python/valuecell/core/agent/connect.py	Connection manager for starting/stopping agents
python/valuecell/core/agent/tests/test_e2e_demo.py	End-to-end test demonstrating the decorator system
python/pyproject.toml	Added a2a-sdk dependency

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}