CapacityEscapes

The two mechanisms that report above the capacity

2/2 passed in 5ms

Test	What it does	Result
test_ceiling_escapes	b92_ceiling, pricing beam splitting alone, crosses the repeaterless capacity at transmittance 0.120257 and is 4.87 times it at 1e-4, while b92_plain stays under it.	✅ pass
test_dialled_escapes	cow_rate at a supplied zero phase error crosses the repeaterless capacity at mu = 1/ln 2 = 1.4427 and sits at 0.693 of it at mu = 1.	✅ pass