Change AbstractTopology to AbstractTopology{N} where N is node count.
This implements ADR-002 (November 13, 2025) decision: node count comes
from mesh connectivity and should be captured in the type for
compile-time optimization.
Benefits:
- Enables Val(N) for zero-allocation ntuple operations
- Allows loop unrolling for small N (8, 20, 27 nodes typical)
- Type-stable operations based on node count
- Node count known from mesh before basis selection
Documentation updates:
- Add Type Parameter section with examples
- Add Rationale section explaining performance benefits
- Reference ADR-002 for design decision details
Concrete types updated in subsequent commits:
Hexahedron{N}, Tetrahedron{N}, Triangle{N}, etc.
Jukka Aho
b2d25e9491