feat(line): 智电改造线路台账接入 ICC 消防探测器真实同步

- 重建 electric_line 表结构（迁移20261024_icc_line_rebuild.sql并同步db_init/db_seed）：删building_id/floor_no/location/icc_device_code占位字段，equip_id改可空，新增imei/gateway_id/type_code/type_name/fire_system_code/fire_system_name/part_unit_loop_code/channel_no/channel_sn/produce_date，gateway_id外键→electric_gateway
- 同步服务IccLineSyncService复用OAuth2真实鉴权分页拉取探测器（POST /detector/subsystem/page，pageSize=50短页停止），按line_code(detectorCode)幂等upsert写icc_sync_log；customer_id由orgCode→customer.icc_code解析、gateway_id由parentCode→electric_gateway.device_code匹配、equip_id同步不填充
- 列表接口返回gateway/type/imei等新字段，keyword检索含imei；前端台账页更新为新列（IMEI/所属网关/探测器类型/回路通道/消防系统/生产日期），保留手动同步按钮与筛选
- 更新系统设计文档electric_line表定义与spec（add-icc-line-sync）

database/db_seed.sql

@@ -493,6 +493,14 @@ CREATE INDEX IF NOT EXISTS idx_gateway_customer ON electric_gateway (customer_id
 CREATE INDEX IF NOT EXISTS idx_gateway_equip    ON electric_gateway (equip_id);
 CREATE INDEX IF NOT EXISTS idx_gateway_imei     ON electric_gateway (icc_imei);
 
+-- 智电改造线路表：gateway_id 外键补充（FK 由迁移/本段建立；db_init.sql 中为普通 BIGINT）
+DO $$
+BEGIN
+  IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'fk_line_gateway' AND conrelid = 'electric_line'::regclass) THEN
+    ALTER TABLE electric_line ADD CONSTRAINT fk_line_gateway FOREIGN KEY (gateway_id) REFERENCES electric_gateway(id);
+  END IF;
+END $$;
+
 -- 菜单 62：设备监控下的智电改造网关台账菜单
 INSERT INTO sys_menu (id, parent_id, menu_name, menu_path, component, icon, sort_order, menu_type, permission, visible) VALUES
 (62, 4,  '智电改造网关台账', '/device/gateway', 'device/gateway/index', 'ApiOutlined', 3, 2, 'device:list', 1)