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/data/equipment/swords.ts

@@ -12,6 +12,7 @@ export const SWORD_EQUIPMENT: Record<string, EquipmentType> = {
     slot: 'mainHand',
     baseCapacity: 30,
     description: 'A simple iron sword. Can be enchanted with elemental effects.',
+    stats: { baseDamage: 8, attackSpeed: 1.2 },
   },
   steelBlade: {
     id: 'steelBlade',
@@ -20,6 +21,7 @@ export const SWORD_EQUIPMENT: Record<string, EquipmentType> = {
     slot: 'mainHand',
     baseCapacity: 40,
     description: 'A well-crafted steel sword. Balanced for combat and enchanting.',
+    stats: { baseDamage: 12, attackSpeed: 1.3 },
   },
   crystalBlade: {
     id: 'crystalBlade',
@@ -28,6 +30,7 @@ export const SWORD_EQUIPMENT: Record<string, EquipmentType> = {
     slot: 'mainHand',
     baseCapacity: 55,
     description: 'A blade made of crystallized mana. Excellent for elemental enchantments.',
+    stats: { baseDamage: 18, attackSpeed: 1.1 },
   },
   arcanistBlade: {
     id: 'arcanistBlade',
@@ -36,6 +39,7 @@ export const SWORD_EQUIPMENT: Record<string, EquipmentType> = {
     slot: 'mainHand',
     baseCapacity: 65,
     description: 'A sword forged for battle mages. High capacity for powerful enchantments.',
+    stats: { baseDamage: 22, attackSpeed: 1.4 },
   },
   voidBlade: {
     id: 'voidBlade',
@@ -44,5 +48,6 @@ export const SWORD_EQUIPMENT: Record<string, EquipmentType> = {
     slot: 'mainHand',
     baseCapacity: 50,
     description: 'A blade corrupted by void energy. Powerful but consumes more mana.',
+    stats: { baseDamage: 25, attackSpeed: 1.0 },
   },
 };

src/lib/game/data/equipment/types.ts

@@ -27,4 +27,8 @@ export interface EquipmentType {
   baseCapacity: number;
   description: string;
   twoHanded?: boolean;         // If true, weapon occupies both main hand and offhand slots
+  stats?: {
+    baseDamage?: number;     // Base damage per hit (swords)
+    attackSpeed?: number;    // Attacks per in-game hour (swords)
+  };
 }