feat(ai): 添加 ai_tenant_configs 迁移 + Entity

支持租户级 Provider 路由配置、月度 Token 预算、每日患者限制
unique 索引确保每租户一条配置，迁移号 000117

crates/erp-server/migration/src/lib.rs

@@ -116,6 +116,7 @@ mod m20260505_000113_create_ble_gateways;
 mod m20260505_000114_dialysis_record_add_workflow_instance;
 mod m20260505_000115_family_member_health_proxy;
 mod m20260505_000116_seed_missing_health_menus;
+mod m20260505_000117_create_ai_tenant_configs;
 
 pub struct Migrator;
 
@@ -239,6 +240,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260505_000114_dialysis_record_add_workflow_instance::Migration),
             Box::new(m20260505_000115_family_member_health_proxy::Migration),
             Box::new(m20260505_000116_seed_missing_health_menus::Migration),
+            Box::new(m20260505_000117_create_ai_tenant_configs::Migration),
         ]
     }
 }