[math-01] Inventory formulas and lock KAMEL conventions

[krystophny]

Summary

• add a formula index mapping thesis equations to code consumers
• lock phase, Fourier, units, species, and sign conventions in executable Mathematica checks
• add shared deterministic verification helpers and Makefile wiring

Why

Later physics changes have an explicit convention baseline and traceable source map.

Validation

Validated cumulatively at the stack head:

• cmake --build build -j2
• ctest --test-dir build -E 'test_rhs_balance|test_periodic_convergence|test_periodic_vs_global' --output-on-failure — 35/35 passed

Known red gates are intentionally excluded from that command: the pre-existing test_rhs_balance baseline failure, the periodization-deformation acceptance gate, and the unresolved periodic-vs-global 5% agreement gate.

Stack

Base: fix/kim-fp-37-parallel-flow
Head: fix/kim-fp-193-conventions

Closes #193

[marjohma]

Closing this draft because GitHub cannot change a pull request author in place. It will be recreated unchanged using Markus Markl's marjohma credentials.

[marjohma]

Replacement authored by Markus Markl (@marjohma): #222