feat: Add Anthropic (Claude) LLM support

[tonycdr-prog]

Summary

Adds support for Anthropic Claude models as requested in #7.

Changes

• Add Anthropic support to LLMFactory.create_llm_and_embeddings()
• Support Claude models: claude-3-5-sonnet, claude-3-5-haiku, claude-3-opus
• Short names mapped to full Anthropic model IDs
• Uses langchain_anthropic.ChatAnthropic for LLM
• Embeddings via OpenAI fallback or Ollama (Anthropic doesn't provide embeddings)
• Updated extract_response() to handle Anthropic response format
• Added langchain-anthropic dependency

Usage

from agent_assembly_line.config import Config
from agent_assembly_line.llm_factory import LLMFactory

# Set your API key
os.environ['ANTHROPIC_API_KEY'] = 'your-key'

# Create config with Anthropic
config = Config(llm_type='anthropic', model_name='claude-3-5-sonnet')
llm, embeddings = LLMFactory.create_llm_and_embeddings(config)

Testing

Tested locally with Claude 3.5 Sonnet. Works with the existing agent patterns.

Closes #7