New "imagine" and "calculate" commands
Implemented image sending
Moved OpenAI specific code to OpenAI class
Abstracted away OpenAI API in bot class
Minor fixes
Switched from sqlite3 to DuckDB
Added comments to config template
Added more options to configuration
Added systemd service file
Added migration logging to database
Added command handling for help, room creation, stats, bot info
Improved context handling
Added some config checks
Added auto-detection of bot's Matrix user ID
Added more info to README