fix(backend): add products.min_quantity migration to runMigrations()

The ensureColumn call was written as dead comments (lines 6242-6273) but
never actually executed inside runMigrations(), so the production DB
was missing the column. This adds the call at the end of runMigrations()
so it runs on next startup.

cfc-backend/src/main/java/com/etotem/cfc/config/DatabaseInitializer.java

@@ -6414,6 +6414,9 @@ private void runMigration98() {
 	} catch (Exception e) {
 		// 列已存在，忽略错误
 	}
+
+	// 迁移: products表添加min_quantity列（商品最小购买数限制）
+	ensureColumn("products", "min_quantity", "INT DEFAULT 1 COMMENT '最小购买数量限制'");
 }
 
 private void runMigration99() {