Convert readScroll to a per-scroll handler table (refactor step 7)

The read_scroll switch becomes gameData.readHandlers, indexed by
ScrollKind; the five identify scrolls share one handler. The magic
mapping cell logic is extracted into revealSpot. Effect order and RNG
call sequence unchanged.

game/tables.go

@@ -127,6 +127,11 @@ type gameData struct {
 	// the cases of the potions.c quaff switch. The bool is trip — was
 	// the hero hallucinating when the potion went down.
 	quaffHandlers [NumPotionTypes]func(g *RogueGame, trip bool)
+
+	// readHandlers dispatches each scroll kind to its effect method:
+	// the cases of the scrolls.c read_scroll switch. The handler gets
+	// the scroll being read (the identify family needs its subtype).
+	readHandlers [NumScrollTypes]func(g *RogueGame, obj *Object)
 }
 
 // ripWall is the repeated blank wall line of the tombstone art.
@@ -609,6 +614,27 @@ func newGameData() *gameData {
 			PotionBlindness:       (*RogueGame).quaffBlindness,
 			PotionLevitation:      (*RogueGame).quaffLevitation,
 		},
+
+		readHandlers: [NumScrollTypes]func(*RogueGame, *Object){
+			ScrollMonsterConfusion:    (*RogueGame).readMonsterConfusion,
+			ScrollMagicMapping:        (*RogueGame).readMagicMapping,
+			ScrollHoldMonster:         (*RogueGame).readHoldMonster,
+			ScrollSleep:               (*RogueGame).readSleep,
+			ScrollEnchantArmor:        (*RogueGame).readEnchantArmor,
+			ScrollIdentifyPotion:      (*RogueGame).readIdentify,
+			ScrollIdentifyScroll:      (*RogueGame).readIdentify,
+			ScrollIdentifyWeapon:      (*RogueGame).readIdentify,
+			ScrollIdentifyArmor:       (*RogueGame).readIdentify,
+			ScrollIdentifyRingOrStick: (*RogueGame).readIdentify,
+			ScrollScareMonster:        (*RogueGame).readScareMonster,
+			ScrollFoodDetection:       (*RogueGame).readFoodDetection,
+			ScrollTeleportation:       (*RogueGame).readTeleportation,
+			ScrollEnchantWeapon:       (*RogueGame).readEnchantWeapon,
+			ScrollCreateMonster:       (*RogueGame).readCreateMonster,
+			ScrollRemoveCurse:         (*RogueGame).readRemoveCurse,
+			ScrollAggravateMonsters:   (*RogueGame).readAggravateMonsters,
+			ScrollProtectArmor:        (*RogueGame).readProtectArmor,
+		},
 	}
 }