refactor(scenario): delete predator_evade; template is the canonical scenario

refactor: restructure proteus into game/web subpackages

feat(runtime): auto-regressive play — handover memory every turn + the model's own prior moves in each observation (Markovian -> auto-regressive)

feat(cp7): hybrid memory injection into SessionRunner turn-1 observation

feat(cp7): additive SessionTrace.memory_ref