feat: implement sword/melee auto-attack system (spec §3.1, §4.3)

- Add calcMeleeDamage() with elemental matchup for enchanted swords
- Add meleeSwordProgress per-instance accumulator to combat state
- Add melee branch in processCombatTick (no mana cost, no Executioner/Berserker)
- Add baseDamage/attackSpeed stats to all 5 sword types
- Wire equippedSwords through gameStore to combat tick pipeline
- 16 new regression tests, all 937 tests pass

src/lib/game/constants/index.ts

@@ -21,6 +21,9 @@ export type { RoomType } from '../types/game';
 export { PUZZLE_ROOM_INTERVAL, SWARM_ROOM_CHANCE, SPEED_ROOM_CHANCE, PUZZLE_ROOM_CHANCE } from './rooms';
 export { PUZZLE_ROOMS, SWARM_CONFIG, SPEED_ROOM_CONFIG, FLOOR_ARMOR_CONFIG } from './rooms';
 
+// Equipment types
+export { EQUIPMENT_TYPES } from '../data/equipment/equipment-types-data';
+
 // Room type display labels
 export const ROOM_TYPE_LABELS: Record<string, { label: string; icon: string; color: string }> = {
   combat: { label: 'Combat', icon: '⚔️', color: '#EF4444' },