Move the reel-out flight loop from examples/simple_reelout.jl into src/ #13

The reel-out coupling loop (entry, reel-out with soft start, figure-eight phase and soft stop, examples/simple_reelout.jl L377–583, with the winch adapter in examples/winch_adapter.jl) exists only as an example script, so a package that wants to fly SKC's reel-out on a model has to copy it.

1-Bart-1/BridleBalance.jl#2 does exactly that: src/flight.jl holds a condensed copy over SKC's exported controllers, without the entry force guard and the soft stop, so its flights differ from SKC's reference flights.

Proposal: move the loop into src/ as an exported function taking the model's step callback and the controller settings, keep examples/simple_reelout.jl as a thin caller, and let BridleBalance delete its copy.