test: PR32测试 — 配件价值、折扣率、套装成本低于单买

新增8个测试:
- 4个配件价值验证(芳香无配件/家庭475/居家585/全精油795)
- 折扣率<1、全精油≈0.69、大套装折扣更好
- 套装成本≤单买成本

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/__tests__/kitCost.test.js

@@ -251,3 +251,80 @@ describe('Recipe Matching', () => {
     expect(canMakeRecipe(kit, recipe)).toBe(false)
   })
 })
+
+// ---------------------------------------------------------------------------
+// Accessory Values — PR32
+// ---------------------------------------------------------------------------
+describe('Accessory Values', () => {
+  it('芳香调理 has no accessories', () => {
+    const kit = KITS.find(k => k.id === 'aroma')
+    expect(kit.accessoryValue).toBeUndefined()
+  })
+
+  it('家庭医生 accessories = 475 (香薰机375 + 木盒100)', () => {
+    const kit = KITS.find(k => k.id === 'family')
+    expect(kit.accessoryValue).toBe(475)
+  })
+
+  it('居家呵护 accessories = 585 (香薰机375 + 竹木架210)', () => {
+    const kit = KITS.find(k => k.id === 'home3988')
+    expect(kit.accessoryValue).toBe(585)
+  })
+
+  it('全精油 accessories = 795 (香薰机375 + 竹木架210×2)', () => {
+    const kit = KITS.find(k => k.id === 'full')
+    expect(kit.accessoryValue).toBe(795)
+  })
+})
+
+// ---------------------------------------------------------------------------
+// Discount Rate Calculation — PR32
+// ---------------------------------------------------------------------------
+describe('Discount Rate', () => {
+  function calcDiscountRate(kit) {
+    const resolved = kit.oils.map(resolveOilName)
+    const bc = kit.bottleCount || {}
+    let totalBP = 0
+    for (const name of resolved) {
+      const meta = oils[name]
+      totalBP += meta ? meta.bottlePrice * (bc[name] || 1) : 0
+    }
+    const totalValue = totalBP + (kit.accessoryValue || 0)
+    return totalValue > 0 ? Math.min(kit.price / totalValue, 1) : 1
+  }
+
+  it('all kits have discount rate < 1 (套装比单买便宜)', () => {
+    for (const kit of KITS) {
+      const rate = calcDiscountRate(kit)
+      expect(rate).toBeLessThan(1)
+      expect(rate).toBeGreaterThan(0)
+    }
+  })
+
+  it('全精油 discount rate ≈ 0.69', () => {
+    const kit = KITS.find(k => k.id === 'full')
+    const rate = calcDiscountRate(kit)
+    expect(rate).toBeGreaterThan(0.65)
+    expect(rate).toBeLessThan(0.75)
+  })
+
+  it('larger kits have better discounts', () => {
+    const rates = KITS.map(k => ({ id: k.id, rate: calcDiscountRate(k), count: k.oils.length }))
+    rates.sort((a, b) => a.count - b.count)
+    // Generally larger kits should have lower discount rate (better deal)
+    // At minimum, the largest kit should have a lower rate than the smallest
+    expect(rates[rates.length - 1].rate).toBeLessThanOrEqual(rates[0].rate)
+  })
+
+  it('kit cost per recipe should be less than original cost', () => {
+    for (const kit of KITS) {
+      const perDrop = calcKitPerDrop(kit)
+      const recipes = prodData.recipes.filter(r => canMakeRecipe(kit, r))
+      for (const r of recipes.slice(0, 5)) {
+        const kitCost = calcRecipeCostWithKit(perDrop, r)
+        const originalCost = calcOriginalCost(r)
+        expect(kitCost).toBeLessThanOrEqual(originalCost + 0.01)
+      }
+    }
+  })
+})