feat(proxy): Add proxy configuration support

[liangzhang-keepmoving]

Description

Adds proxy configuration support to the memU project, allowing users to configure HTTP proxies for LLM and embedding clients. This feature addresses the issue of Telegram connection difficulties in some regions by enabling proxy settings.

Changes Made

1. Added proxy configuration option in LLMConfig model (src/memu/app/settings.py)
2. Updated service initialization to pass proxy config to LLM clients (src/memu/app/service.py)
3. Modified HTTPLLMClient to accept and use proxy parameter (src/memu/llm/http_client.py)
4. Updated OpenAISDKClient to support proxy configuration via httpx (src/memu/llm/openai_sdk.py)
5. Added proxy support to LazyLLMClient (src/memu/llm/lazyllm_client.py)

Usage Example

from memu.app import MemoryService

# Create service with proxy configuration
service = MemoryService(
    llm_profiles={
        "default": {
            "api_key": "your_api_key",
            "proxy": "http://your-proxy-server:8080"  # Proxy configuration
        }
    },
    # Other configurations...
)

Benefits

• Solves Telegram connection issues in regions with restricted access
• Provides flexible proxy settings for all LLM providers
• Supports all client backends (httpx, SDK, lazyllm)
• Maintains backward compatibility - proxy is optional

References

• Issue [FEATURE] 支持代理配置 #349: [FEATURE] 支持代理配置