Eyring: thermoneutral ΔG‡ = 0 ⇒ k = k_B·T/h (universal frequency ceiling)

Sympy-exact symbolic witness of the Eyring TST universal-frequency anchor. Setup: k = k_B·T/h · exp(-ΔG‡/(R·T)) as a sympy expression with k_B, h, R, T, ΔG‡ all positive symbols. Thermoneutral-barrier anchor: k.subs(ΔG‡, 0) → k_B·T/h…