feat(profiler/behave_shell): G.6 emotional_valence.arousal

high_agitated when any of:
  * caps_run_max ≥ 5
  * bang_run_max ≥ 3
  * fastest typing burst median IAT < 0.06s with ≥ 30 IATs total

low_calm when slowest qualifying burst median IAT > 0.30s with ≥ 30
IATs. Else medium_engaged. Confidence hard-capped at 0.5; 0.30 below
AROUSAL_MIN_IATS.

decnet/profiler/behave_shell/_features/__init__.py

@@ -25,6 +25,7 @@ from decnet.profiler.behave_shell._features.cognitive import (
     inter_command_latency_class,
 )
 from decnet.profiler.behave_shell._features.emotional_valence import (
+    arousal,
     valence,
 )
 from decnet.profiler.behave_shell._features.environmental import (
@@ -95,4 +96,5 @@ FEATURES: tuple[FeatureFn, ...] = (
     cleanup_behavior,
     multi_actor_indicators,
     valence,
+    arousal,
 )