fix(test): 修复测试文件类型错误和测试数据库 schema 过期问题

- 修正 stock_in/out 测试中 WarehouseID/ProductID 指针误用（StockOrder 用 uint64，Inventory 用 *uint64）
- 更新 testutil/setup.go：inventories 表加入所有批次字段，stock_in_items 加 production_date，新增 finance_records 表
- 修正 inventory handler 中 DATE_FORMAT（MySQL 专属）→ DATE()（跨 DB 兼容）
- 更新断言：order_no 前缀改为 RK，库存总量用 SUM 替代 First
- 库存 List 新增 in_stock=1 过滤器

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/testutil/setup.go

@@ -183,6 +183,7 @@ func SetupTestDB() *gorm.DB {
 			unit_price REAL DEFAULT 0,
 			total_price REAL DEFAULT 0,
 			batch_no TEXT,
+			production_date DATETIME,
 			custom_fields TEXT,
 			remark TEXT
 		)`,
@@ -223,11 +224,25 @@ func SetupTestDB() *gorm.DB {
 		`CREATE TABLE IF NOT EXISTS inventories (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			shop_id INTEGER NOT NULL,
-			warehouse_id INTEGER NOT NULL,
-			product_id INTEGER NOT NULL,
+			warehouse_id INTEGER,
+			product_id INTEGER,
+			stock_in_item_id INTEGER,
+			inventory_check_id INTEGER,
 			quantity REAL DEFAULT 0,
+			product_code TEXT DEFAULT '',
+			product_name TEXT DEFAULT '',
+			series TEXT DEFAULT '',
+			spec TEXT DEFAULT '',
+			unit TEXT DEFAULT '',
+			warehouse_name TEXT DEFAULT '',
+			unit_price REAL,
+			production_date DATETIME,
+			batch_no TEXT DEFAULT '',
+			supplier_name TEXT DEFAULT '',
+			remark TEXT DEFAULT '',
+			created_at DATETIME,
 			updated_at DATETIME,
-			UNIQUE(shop_id, warehouse_id, product_id)
+			deleted_at DATETIME
 		)`,
 		`CREATE TABLE IF NOT EXISTS inventory_logs (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -269,6 +284,24 @@ func SetupTestDB() *gorm.DB {
 			actual_qty REAL,
 			remark TEXT
 		)`,
+		`CREATE TABLE IF NOT EXISTS finance_records (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			created_at DATETIME,
+			updated_at DATETIME,
+			deleted_at DATETIME,
+			shop_id INTEGER NOT NULL,
+			partner_id INTEGER,
+			type TEXT,
+			amount REAL DEFAULT 0,
+			balance REAL DEFAULT 0,
+			status TEXT DEFAULT 'open',
+			ref_type TEXT,
+			ref_id INTEGER,
+			operator_id INTEGER,
+			record_date DATETIME,
+			remark TEXT,
+			custom_fields TEXT
+		)`,
 		`CREATE TABLE IF NOT EXISTS number_rules (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			shop_id INTEGER NOT NULL,