Route the bull's hits through the typed DamageEvent pipeline

Hitbox now builds a DamageEvent (cause + hit position + shaped knock-up) and
calls the bull's new receive_damage(), instead of two stringly Object.call()s.
receive_damage adapts over the existing pip/knock-up logic so behaviour is
identical -- the characterization test drives both the string and typed paths
and asserts the same outcomes. Wire fx/damage/harness tests into run_tests.sh
+ CLAUDE.md. All hitbox guard tests green (stab, bear hitbox, ram, charge).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CmG3mQGVXZUPDVapmdbWZ1

player.gd

@@ -1222,6 +1222,15 @@ func apply_knock_up(v: float) -> void:
 	velocity.y = maxf(velocity.y, v)
 
 
+# Typed entry point for the unified hit pipeline: a Hitbox (or any attacker) hands the bull a
+# DamageEvent instead of calling take_sword_hit directly. A thin adapter over the existing pip /
+# knock-up logic, so behaviour is unchanged while callers migrate off the stringly path.
+func receive_damage(event: DamageEvent) -> void:
+	take_sword_hit(event.cause_name(), event.hit_position)
+	if event.knock_up > 0.0:
+		apply_knock_up(event.knock_up)
+
+
 # Blood spurt from a spear wound: a short-lived spray of dark-red gobs flung out of the
 # entry point, biased outward from the bull's centre (so it reads as bursting from the
 # hide) with a touch of lift before gravity drags it down.