docs: Add comprehensive API reference documentation

Complete API reference covering all public modules:
- memdocs.extract: Code extraction and symbol parsing
- memdocs.summarize: AI-powered summarization with Claude
- memdocs.index: Memory indexing and retrieval
- memdocs.search: Local vector search with FAISS
- memdocs.embeddings: Local embedding generation
- memdocs.guard: PHI/PII detection and redaction
- memdocs.security: Input validation or rate limiting
- memdocs.schemas: Pydantic models for data validation
- memdocs.exceptions: Custom exceptions with suggestions
- MCP Server: AI assistant integration
- Empathy Framework adapter

Includes code examples for all major classes and methods.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: 2 people