Refactor code style, comments, and robot implementations

Move UML PDF to doc/ and update .gitignore. Normalize includes,
whitespace and function signatures across headers/sources and add
concise class/function documentation. Fix RandomBot so the mine
limit is computed once and simplify DigDeepBot/SortBot mining logic.
Tidy World/Game initialization, error handling, and minor const/var
clarifications for readability and correctness

include/SortBot.h

@@ -2,9 +2,10 @@
 
 #include "../include/BaseRobot.h"
 
+/* Robot that reorders the current column so the highest value reaches the surface,
+   then mines that top block. */
 class SortBot : public BaseRobot {
   public:
     SortBot ( int startX, int startY );
     int mine ( World &world ) override;
 };
-