- add PaginationQueryDto<TOrderBy> generic with orderBy and orderDir fields
- add SessionOrderBy, EnvironmentOrderBy, ScenarioOrderBy type aliases
- update session, environment, scenario services and controllers to use typed pagination
- update MCP list_sessions, list_environments, list_scenarios tools to expose orderBy/orderDir
- update tests for all list endpoints to cover page, limit, ordering, and invalid param rejection