Move bull ability FX into the authorable systems/fx/ library

The bull's kick/dash/slam/roll and movement particles were ~112 lines of
hand-built CPUParticles3D in player.gd, bypassing the Fx system entirely
(Fx.spawn had zero callers) — so Siim couldn't author them in the inspector.

- Add six inspector-editable effect scenes (bull_slam/kick/dash one-shots +
  bull_hoof_dust/charge_trail/roll_sparks continuous); wire player.gd to
  Fx.spawn() / new Fx.attach(); register them + the gallery + smoke test.
- Extract the coded, non-particle slam rings + kick flash into a new
  bull_impact_fx.gd component (bull_legs.gd pattern).
- Drop 12 now-obsolete DP dust look-params (the .tscn owns the look now).
- Trim god-file comment noise: rewrite an AI-placeholder barrel block to typed
  code, drop dead commented-out bounce/topple code, fix stale post-reorg file
  paths (Assets/… → art/…, PascalCase scene names → snake_case).
- Document the Siim workflow in systems/fx/README.md; update CLAUDE.md.

player.gd 1307 → 944 lines. Full suite green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CCyaJPTHCH9EDthpf4A5Sj

actors/bear/bear.gd

@@ -26,11 +26,11 @@ var _phase: Phase = Phase.WINDUP
 var _bull: CharacterBody3D = null
 var _skeleton: Skeleton3D = null
 var _anim_player: AnimationPlayer = null
-# Separate player baked into Assets/fx/Bear_FX.glb: each clip scales one FX mesh up from 0
+# Separate player baked into art/fx/bear_fx.glb: each clip scales one FX mesh up from 0
 # and back at its strike frame (self-hiding), so bear.gd just fires the matching clip.
 var _fx_player: AnimationPlayer = null
 var _fx_root: Node = null
-# Shaped attack colliders live in BearAttackHitboxes.tscn (under bear_model, so they track the
+# Shaped attack colliders live in bear_attack_hitboxes.tscn (under bear_model, so they track the
 # bear's facing): a ground-circle cylinder for the leap slam and a forward box lane for the smash.
 # Their sizes AND their travel/pop motion are authored in that scene's AnimationPlayer (clips
 # "leap_slam" / "smash_travel") — scrub them there to tweak. bear.gd only fires the clip, sets the
@@ -635,7 +635,7 @@ func _try_hit(reach: float) -> bool:
 	return true
 
 
-# Grab the designer-authored collider sub-scene (BearAttackHitboxes.tscn instanced under
+# Grab the designer-authored collider sub-scene (bear_attack_hitboxes.tscn instanced under
 # bear_model) and park both hitboxes deactivated. Shapes + travel are authored in that scene.
 func _setup_attack_hitboxes() -> void:
 	var root := _mesh.get_node_or_null("AttackHitboxes") if _mesh else null
@@ -920,18 +920,6 @@ func _die(hit_dir: Vector3) -> void:
 	velocity = Vector3.ZERO
 	_blood_burst.burst(global_position + Vector3(0.0, 1.4, 0.0), hit_dir)
 	_play(_anim_death)
-	# No death clip on the rig — topple the beast onto its side (about the hit direction,
-	# so it falls the way it was struck) and sink it away, then free.
-	#var fall_axis := Vector3(-hit_dir.z, 0.0, hit_dir.x)
-	#if fall_axis.length() < 0.01:
-	#	fall_axis = Vector3.RIGHT
-	#var tween := create_tween()
-	#tween.tween_property(_mesh, "rotation",
-	#	_mesh.rotation + fall_axis.normalized() * deg_to_rad(88.0), 0.7)\
-	#	.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_IN)
-	#tween.tween_interval(2.5)
-	#tween.tween_property(_mesh, "position:y", _mesh.position.y - 3.0, 1.0)
-	#tween.tween_callback(queue_free)
 
 
 # ── Interface shared with the matador (guarded elsewhere via has_method) ─────────────