feat: 新增数据库迁移，重命名 device_no 为 virtual_no，新增 iot_card.virtual_no 和 package.virtual_ratio 字段

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

migrations/000075_add_virtual_ratio_to_package.up.sql

@@ -0,0 +1,11 @@
+ALTER TABLE tb_package ADD COLUMN IF NOT EXISTS virtual_ratio DECIMAL(18,6) NOT NULL DEFAULT 1.0;
+
+COMMENT ON COLUMN tb_package.virtual_ratio IS '虚流量比例(real_data_mb/virtual_data_mb)，创建套餐时计算存储，默认1.0';
+
+UPDATE tb_package
+SET virtual_ratio = CASE
+    WHEN enable_virtual_data = true AND virtual_data_mb > 0
+        THEN (real_data_mb::DECIMAL / virtual_data_mb::DECIMAL)
+    ELSE 1.0
+END
+WHERE deleted_at IS NULL;