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/lib/game/crafting-fabricator.ts

@@ -6,6 +6,7 @@ import type { ElementState } from './types';
 import type { FabricatorRecipe } from './data/fabricator-recipes';
 import { FABRICATOR_RECIPES } from './data/fabricator-recipes';
 import { useManaStore } from './stores/manaStore';
+import { computeDisciplineEffects } from './effects/discipline-effects';
 
 // ─── Lookup ───────────────────────────────────────────────────────────────────
 
@@ -13,6 +14,27 @@ export function getFabricatorRecipe(recipeId: string): FabricatorRecipe | undefi
   return FABRICATOR_RECIPES.find(r => r.id === recipeId);
 }
 
+// ─── Crafting Cost Reduction ──────────────────────────────────────────────────
+
+/**
+ * Returns the current crafting cost reduction percentage from discipline effects.
+ * Spec: actualCost = baseCost × (1 - craftingCostReduction / 100), capped at 75%.
+ */
+export function getCraftingCostReduction(): number {
+  const disciplineEffects = computeDisciplineEffects();
+  const raw = disciplineEffects.bonuses.craftingCostReduction || 0;
+  return Math.min(75, raw);
+}
+
+/**
+ * Apply cost reduction to a material amount, rounding up to ensure
+ * the player never pays more than the displayed reduced cost.
+ */
+export function applyCostReduction(baseAmount: number, costReduction: number): number {
+  if (costReduction <= 0) return baseAmount;
+  return Math.max(1, Math.ceil(baseAmount * (1 - costReduction / 100)));
+}
+
 // ─── Cost Check ───────────────────────────────────────────────────────────────
 
 export interface FabricatorCostCheck {
@@ -26,11 +48,14 @@ export function checkFabricatorCosts(
   materials: Record<string, number>,
   rawMana: number,
   elements: Record<string, ElementState>,
+  costReduction?: number,
 ): FabricatorCostCheck {
+  const reduction = costReduction ?? getCraftingCostReduction();
   const missingMaterials: Record<string, number> = {};
   let canCraft = true;
 
-  for (const [matId, required] of Object.entries(recipe.materials)) {
+  for (const [matId, rawRequired] of Object.entries(recipe.materials)) {
+    const required = applyCostReduction(rawRequired, reduction);
     const available = materials[matId] || 0;
     if (available < required) {
       missingMaterials[matId] = required - available;
@@ -116,9 +141,12 @@ export function refundFabricatorMana(
 export function deductMaterials(
   recipe: FabricatorRecipe,
   materials: Record<string, number>,
+  costReduction?: number,
 ): Record<string, number> {
+  const reduction = costReduction ?? getCraftingCostReduction();
   const newMaterials = { ...materials };
-  for (const [matId, amount] of Object.entries(recipe.materials)) {
+  for (const [matId, rawAmount] of Object.entries(recipe.materials)) {
+    const amount = applyCostReduction(rawAmount, reduction);
     newMaterials[matId] = (newMaterials[matId] || 0) - amount;
     if (newMaterials[matId] <= 0) delete newMaterials[matId];
   }