Refactor large files into modular components

- Refactored page.tsx (613→252 lines) with GameOverScreen and LeftPanel extracted
- Refactored StatsTab.tsx (584→92 lines) with section components
- Refactored SkillsTab.tsx (434→54 lines) with sub-components
- Created modular structure for GameContext, LootInventory, and other components
- All extracted components organized into feature directories

src/lib/game/crafting-actions/design-actions.ts

@@ -0,0 +1,113 @@
+// ─── Enchantment Design Actions ────────────────────────────────────────────
+
+import type { GameState, EnchantmentDesign, DesignEffect } from '../types';
+import * as CraftingUtils from '../crafting-utils';
+import * as CraftingDesign from '../crafting-design';
+import { computeEffects } from '../upgrade-effects';
+import { hasSpecial, SPECIAL_EFFECTS } from '../special-effects';
+
+export function startDesigningEnchantment(
+  name: string,
+  equipmentTypeId: string,
+  effects: DesignEffect[],
+  get: () => GameState,
+  set: (fn: (state: GameState) => Partial<GameState>) => void
+): boolean {
+  const state = get();
+  const enchantingLevel = state.skills.enchanting || 0;
+  const validation = CraftingDesign.validateDesignEffects(
+    effects,
+    equipmentTypeId,
+    enchantingLevel
+  );
+  if (!validation.valid) return false;
+
+  const equipType = CraftingUtils.getEquipmentType(equipmentTypeId);
+  if (!equipType) return false;
+
+  const efficiencyBonus = ((state.skillUpgrades || {})['efficientEnchant'] || [])?.length * 0.05 || 0;
+  const totalCapacityCost = CraftingDesign.calculateDesignCapacityCost(effects, efficiencyBonus);
+
+  if (totalCapacityCost > equipType.baseCapacity) {
+    return false;
+  }
+
+  const computedEffects = computeEffects(state.skillUpgrades || {}, state.skillTiers || {});
+  const hasEnchantMastery = hasSpecial(computedEffects, SPECIAL_EFFECTS.ENCHANT_MASTERY);
+
+  let updates: any = {};
+
+  if (!state.designProgress) {
+    updates = {
+      currentAction: 'design' as const,
+      designProgress: {
+        designId: CraftingUtils.generateDesignId(),
+        progress: 0,
+        required: CraftingDesign.calculateDesignTime(effects),
+        name,
+        equipmentType: equipmentTypeId,
+        effects,
+      },
+    };
+  } else if (hasEnchantMastery && !state.designProgress2) {
+    updates = {
+      designProgress2: {
+        designId: CraftingUtils.generateDesignId(),
+        progress: 0,
+        required: CraftingDesign.calculateDesignTime(effects),
+        name,
+        equipmentType: equipmentTypeId,
+        effects,
+      },
+    };
+  } else {
+    return false;
+  }
+
+  set(() => updates);
+  return true;
+}
+
+export function cancelDesign(
+  get: () => GameState,
+  set: (fn: (state: GameState) => Partial<GameState>) => void
+) {
+  const state = get();
+  if (state.designProgress2 && !state.designProgress) {
+    set(() => ({ designProgress2: null }));
+  } else {
+    set(() => ({
+      currentAction: 'meditate' as const,
+      designProgress: null,
+    }));
+  }
+}
+
+export function saveDesign(
+  design: EnchantmentDesign,
+  get: () => GameState,
+  set: (fn: (state: GameState) => Partial<GameState>) => void
+) {
+  const state = get();
+  if (state.designProgress2 && state.designProgress2.designId === design.id) {
+    set((state) => ({
+      enchantmentDesigns: [...state.enchantmentDesigns, design],
+      designProgress2: null,
+    }));
+  } else {
+    set((state) => ({
+      enchantmentDesigns: [...state.enchantmentDesigns, design],
+      designProgress: null,
+      currentAction: 'meditate' as const,
+    }));
+  }
+}
+
+export function deleteDesign(
+  designId: string,
+  set: (fn: (state: GameState) => Partial<GameState>) => void
+) {
+  set((state) => ({
+    enchantmentDesigns: state.enchantmentDesigns.filter(d => d.id !== designId),
+  }));
+}