- Simplified and unified constructors for `integrator_t` to improve usability and maintainability.
- Enhanced `find_v_intersections_at_u` with robust handling of vertical edges and improved numerical stability.
- Refactored `is_point_inside_domain` to reuse existing intersection logic, eliminating code duplication.
- Adjusted interface to align with revised expectations around `parametric_plane_t`, which previously caused inconsistencies.
- Extended design to support multi-face integration (previously limited to single face); volume-related logic temporarily commented out for clarity.
This version is compilable, but not yet runnable due to nullptr issues in primitive_process during object creation. Integration framework is now structurally ready for multi-surface extension once initialization is fixed.
mckay