Decompose move.go; traps become a handler table (refactor step 7)

The be_trapped switch becomes gameData.trapHandlers with one trap*
method per trap kind (mystery messages split in two); moveHero splits
into moveTarget/moveResolve/moveEnter/moveOnto/offMap; passageTurn
gains per-axis passageTurnVertical/Horizontal. move.go is
complexity-clean. Behavior and RNG call order unchanged.

game/tables.go

@@ -147,6 +147,10 @@ type gameData struct {
 	// cases of the big command.c switch. Keys that re-dispatch (runs,
 	// fight, repeat, move-on) and wizard keys stay in dispatchKey.
 	commandHandlers map[byte]func(g *RogueGame)
+
+	// trapHandlers dispatches each sprung trap to its effect method:
+	// the cases of the move.c be_trapped switch.
+	trapHandlers [NumTrapTypes]func(g *RogueGame, tc Coord)
 }
 
 // ripWall is the repeated blank wall line of the tombstone art.
@@ -811,6 +815,17 @@ func newGameData() *gameData {
 				g.After = false
 			},
 		},
+
+		trapHandlers: [NumTrapTypes]func(*RogueGame, Coord){
+			TrapDoor:     (*RogueGame).trapFall,
+			TrapArrow:    (*RogueGame).trapArrow,
+			TrapSleep:    (*RogueGame).trapSleep,
+			TrapBear:     (*RogueGame).trapBear,
+			TrapTeleport: (*RogueGame).trapTeleport,
+			TrapDart:     (*RogueGame).trapDart,
+			TrapRust:     (*RogueGame).trapRust,
+			TrapMystery:  (*RogueGame).trapMystery,
+		},
 	}
 }