Paper IX exact verification package

Run:
  ./run_all.sh

Expected headline output:
  acyclic paths = 64
  acyclic structures = 216360
  acyclic feasible through depth 5 = 63240
  acyclic dangerous at depth 6 = 0
  explicit H_Z(4,4) witness: s=4, b=4, first failure depth 5
  two-cycle templates = 192 = 176 generic + 16 exceptional
  self-loop feeder rank-3 assignments = 32, bad = 0
  disconnected self-loop templates = 168, dangerous = 0

Arithmetic:
  C++ acyclic verification uses exact reduced rational arithmetic.
  Python symbolic verifiers use SymPy over QQ.
  No floating-point arithmetic or bounded threshold search is used.
