fix(mcp): pass base_url to Anthropic LLM and OpenAI Embedder clients

[Milofax]

Summary

The LLMClientFactory and EmbedderFactory in factories.py read the api_url from config but don't pass it to the client constructors. This causes:

• AnthropicClient to always use https://api.anthropic.com instead of configured URL
• OpenAIEmbedder to always use https://api.openai.com/v1 instead of configured URL

This breaks self-hosted/proxy setups where users want to route requests through custom endpoints.

Changes

• Pass base_url=config.providers.anthropic.api_url to GraphitiLLMConfig for Anthropic
• Pass base_url=config.providers.openai.api_url to OpenAIEmbedderConfig for OpenAI embedder

Test Plan

• Tested with CLIProxyAPI (Anthropic-compatible proxy) - requests now correctly route to custom endpoint
• Tested with Ollama (OpenAI-compatible embeddings) - embeddings now correctly use custom endpoint

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