Introduced customString and customInteger fields to the Unit class in both backend (C++) and frontend (TypeScript/React). Updated data indexes, interfaces, and API handling to support setting and retrieving these custom fields. Also added UI elements in the unit control menu to display and handle these new properties.
Introduces cargo weight and draw argument properties to units across backend, frontend, and Python API. Adds related commands, data extraction, and registration logic, enabling setting and reading of cargo weight and custom draw arguments for units. Includes new API examples and updates to interfaces, data types, and Lua backend for full feature integration.
Changed the default ROE value in unit.h from OPEN_FIRE_WEAPON_FREE to OPEN_FIRE. Renamed mods.png to image.png in docs/images. Removed an unnecessary blank line in the audio section of olympus.json. Bumped version in version.json from v2.0.3 to v2.0.4.
