New 527-line field interpolation system:
- interpolate_fields(): interpolate all fields and gradients at reference point
- interpolate_field(): interpolate single field
- interpolate_field_value(): interpolate field value only
- Supports scalar and vector fields with gradients
- Zero-allocation @generated function for type stability
- Returns NamedTuple with field values and gradients
- Already integrated in JuliaFEM.jl (line 354)
Provides comprehensive field interpolation for material evaluation at integration points.
Jukka Aho