Add usage instructions for image key extraction, file descriptions
for new modules, and technical details of the three .dat encryption
formats (old XOR, V1, V2).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
New mcp_server.py provides 5 tools (get_recent_sessions, get_chat_history,
search_messages, get_contacts, get_new_messages) via FastMCP stdio transport.
Features on-demand decryption with mtime-based caching and WAL support.
ylytdeng
joshua-deng