New 219-line documentation file explaining:
- Ciarlet's finite element triple (K, P, Σ) and computational implementation
- Element structure with type-stable @generated constructor
- Field specifications for single and multi-field elements
- DOF extraction strategies (flat and structured)
- Local-global DOF mapping for coupled multi-field assembly
- Performance notes showing zero-allocation achievement (5.5 ns)
Documents the Element{K,P,S,N} type and its zero-allocation design philosophy.
Jukka Aho