feat(backend): 库存搜索框支持按生产日期检索

- List 关键词查询在 名称/编码/拼音/首字母 之外增加生产日期匹配
  CAST(COALESCE(DATE(sii.production_date),DATE(inv.production_date)) AS CHAR) LIKE
  支持输入 年/年月/完整日期(2010 · 2010-06 · 2010-06-04)，UI 无需改动
- 口径与列表显示/排序一致（入库明细快照优先，回退库存行快照）
- 加回归测试 TestInventoryHandler_List_SearchByProductionDate

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bupi8Kdqkfx2N5acFsHTx5

backend/internal/handler/inventory.go

@@ -105,9 +105,11 @@ func (h *InventoryHandler) List(c *gin.Context) {
 	specStr := c.Query("spec")
 
 	if keyword != "" {
-		baseWhere += " AND (COALESCE(NULLIF(p.name,''), NULLIF(sii.product_name,''), inv.product_name) LIKE ? OR COALESCE(NULLIF(p.code,''), NULLIF(sii.product_code,''), inv.product_code) LIKE ? OR p.name_pinyin LIKE ? OR p.name_initials LIKE ?)"
+		// 关键词匹配：商品名/拼音/首字母/编码 + 生产日期（对生产日期文本 LIKE，支持 "2010"/"2010-06"/"2010-06-04"）。
+		// 生产日期口径与 SELECT/排序一致：COALESCE(入库明细快照, 库存行快照)。
+		baseWhere += " AND (COALESCE(NULLIF(p.name,''), NULLIF(sii.product_name,''), inv.product_name) LIKE ? OR COALESCE(NULLIF(p.code,''), NULLIF(sii.product_code,''), inv.product_code) LIKE ? OR p.name_pinyin LIKE ? OR p.name_initials LIKE ? OR CAST(COALESCE(DATE(sii.production_date), DATE(inv.production_date)) AS CHAR) LIKE ?)"
 		like := "%" + keyword + "%"
-		args = append(args, like, like, like, like)
+		args = append(args, like, like, like, like, like)
 	}
 	// 商品编码独立筛选（库存屏工具栏第二个搜索框，对齐原型 codeInput）
 	if code := c.Query("code"); code != "" {

backend/internal/handler/inventory_test.go

@@ -316,6 +316,36 @@ func TestInventoryHandler_List_FilterByCode(t *testing.T) {
 	assert.Equal(t, float64(0), parseResponse(w)["total"].(float64))
 }
 
+// 关键词搜索生产日期（库存搜索框扩展：UI 不变，输入年/年月/完整日期即可命中）
+func TestInventoryHandler_List_SearchByProductionDate(t *testing.T) {
+	db := testutil.SetupTestDB()
+	shop := testutil.CreateTestShop(db, "INV_PDATE")
+	user := testutil.CreateTestUser(db, shop.ID, "admin", "pass", "admin")
+	warehouse := testutil.CreateTestWarehouse(db, shop.ID, "Warehouse")
+	p1 := testutil.CreateTestProduct(db, shop.ID, "MaotaiA")
+	p2 := testutil.CreateTestProduct(db, shop.ID, "MaotaiB")
+	token := getAuthToken(user.ID, shop.ID, "admin")
+	r := setupProtectedRouter(db)
+
+	d2010 := &model.Date{Time: time.Date(2010, 6, 4, 0, 0, 0, 0, time.Local)}
+	d1999 := &model.Date{Time: time.Date(1999, 12, 16, 0, 0, 0, 0, time.Local)}
+	require.NoError(t, db.Create(&model.Inventory{ShopID: shop.ID, WarehouseID: &warehouse.ID, ProductID: &p1.ID, Quantity: 10, ProductionDate: d2010}).Error)
+	require.NoError(t, db.Create(&model.Inventory{ShopID: shop.ID, WarehouseID: &warehouse.ID, ProductID: &p2.ID, Quantity: 20, ProductionDate: d1999}).Error)
+
+	// 年份命中一条
+	w := makeRequest(r, "GET", "/api/v1/inventory?keyword=2010", token, nil)
+	assert.Equal(t, float64(1), parseResponse(w)["total"].(float64))
+	// 年-月命中一条
+	w = makeRequest(r, "GET", "/api/v1/inventory?keyword=2010-06", token, nil)
+	assert.Equal(t, float64(1), parseResponse(w)["total"].(float64))
+	// 完整日期命中一条
+	w = makeRequest(r, "GET", "/api/v1/inventory?keyword=1999-12-16", token, nil)
+	assert.Equal(t, float64(1), parseResponse(w)["total"].(float64))
+	// 不存在的日期零命中（同时验证不误伤名称/编码）
+	w = makeRequest(r, "GET", "/api/v1/inventory?keyword=2001", token, nil)
+	assert.Equal(t, float64(0), parseResponse(w)["total"].(float64))
+}
+
 // Summary 月初快照字段：月初数量 = 当前数量 − 本月净流水
 func TestInventoryHandler_Summary_LastMonth(t *testing.T) {
 	db := testutil.SetupTestDB()