Introduce health (hp) and damage handling to Robot/BaseRobot
interfaces. Add SmartBot implementation. Refactor bot mining and
movement to use new World APIs (mine, mineAllPositive,
sortPositiveValues). Simplify RandomBot, DigDeepBot, and SortBot
logic, rename/overhaul World rearrange/display, and fix several
indexing/logic bugs and minor cleanups.
