fix: apply Crafting Efficiency cost reduction to all fabrication paths

- Add getCraftingCostReduction() and applyCostReduction() helpers in crafting-fabricator.ts
- Apply cost reduction in deductMaterials() and checkFabricatorCosts()
- Apply cost reduction in startFabricatorCrafting() and cancelEquipmentCrafting() pipeline
- Update canCraftRecipe() in fabricator-recipes.ts to accept costReduction param
- Update FabricatorSubTab and MaterialRecipeCard UIs to display discounted costs
- Spec formula: actualCost = ceil(baseCost × (1 - craftingCostReduction / 100))

Fixes #316

src/components/game/tabs/CraftingTab/FabricatorSubTab.tsx

@@ -15,6 +15,7 @@ import { LOOT_DROPS, LOOT_RARITY_COLORS } from '@/lib/game/data/loot-drops';
 import { useCraftingStore, useManaStore } from '@/lib/game/stores';
 import type { FabricatorRecipe } from '@/lib/game/data/fabricator-recipes';
 import { DebugName } from '@/components/game/debug/debug-context';
+import { getCraftingCostReduction, applyCostReduction } from '@/lib/game/crafting-fabricator';
 
 const BRANCH_RECIPE_IDS = new Set([
   'oakStaff', 'arcanistStaff', 'battlestaff', 'arcanistCirclet', 'arcanistRobe',
@@ -40,6 +41,7 @@ function RecipeCard({
   elementalMana,
   onCraft,
   isCrafting,
+  costReduction,
 }: {
   recipe: FabricatorRecipe;
   materials: Record<string, number>;
@@ -47,6 +49,7 @@ function RecipeCard({
   elementalMana: Record<string, { current: number; max: number; unlocked: boolean }>;
   onCraft: (recipe: FabricatorRecipe) => void;
   isCrafting: boolean;
+  costReduction: number;
 }) {
   const pool = recipe.manaType === 'raw'
     ? rawMana
@@ -56,6 +59,7 @@ function RecipeCard({
     materials,
     pool,
     recipe.manaType,
+    costReduction,
   );
   const rarityStyle = LOOT_RARITY_COLORS[recipe.rarity];
 
@@ -82,17 +86,26 @@ function RecipeCard({
       <Separator className="bg-gray-700 my-2" />
 
       <div className="text-xs space-y-1">
-        <div className="text-gray-500">Materials:</div>
-        {Object.entries(recipe.materials).map(([matId, amount]) => {
+        <div className="text-gray-500 flex justify-between">
+          <span>Materials:</span>
+          {costReduction > 0 && (
+            <span className="text-cyan-400">-{costReduction}% cost</span>
+          )}
+        </div>
+        {Object.entries(recipe.materials).map(([matId, rawAmount]) => {
+          const reducedAmount = applyCostReduction(rawAmount, costReduction);
           const available = materials[matId] || 0;
+          const hasEnough = available >= reducedAmount;
           const matDrop = LOOT_DROPS[matId];
-          const hasEnough = available >= amount;
 
           return (
             <div key={matId} className="flex justify-between">
               <span>{matDrop?.name ?? matId}</span>
               <span className={hasEnough ? 'text-green-400' : 'text-red-400'}>
-                {available} / {amount}
+                {available} / {reducedAmount}
+                {costReduction > 0 && rawAmount !== reducedAmount && (
+                  <span className="text-gray-500 ml-1">(was {rawAmount})</span>
+                )}
               </span>
             </div>
           );
@@ -156,6 +169,7 @@ export function FabricatorSubTab() {
   }, [selectedManaType, branchFilter, unlockedRecipes]);
 
   const isCrafting = equipmentCraftingProgress !== null;
+  const costReduction = getCraftingCostReduction();
 
   const materialRecipes = useMemo(() => MATERIAL_RECIPES, []);
 
@@ -300,6 +314,7 @@ export function FabricatorSubTab() {
                           elementalMana={elements}
                           onCraft={handleCraft}
                           isCrafting={isCrafting}
+                          costReduction={costReduction}
                         />
                       ))
                     )
@@ -318,6 +333,7 @@ export function FabricatorSubTab() {
                           rawMana={rawMana}
                           elementalMana={elements}
                           onCraft={handleCraft}
+                          costReduction={costReduction}
                         />
                       ))
                     )