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/matador/matador.gd

@@ -74,7 +74,7 @@ const _ANIM_TAUNTS: Array[StringName] = [&"Taunt", &"Taunt_B", &"Taunt_C"]
 # reparents from holster to hand at this point in the animation.
 const _DRAW_GRAB_AT: float = 0.55
 
-# Wrapper scenes (glb + an editor-tweakable hitbox / collider) — see Sword.tscn / Spear.tscn.
+# Wrapper scenes (glb + an editor-tweakable hitbox / collider) — see sword.tscn / spear.tscn.
 const _SWORD_SCENE: PackedScene = preload("res://actors/matador/sword.tscn")
 const _SPEAR_SCENE: PackedScene = preload("res://actors/matador/spear.tscn")
 
@@ -603,7 +603,7 @@ func _tick_attack(delta: float) -> void:
 	if _swing_timer > 0.0:
 		_decelerate(22.0, delta)
 		_play_anim(_ANIM_ATTACK)
-		# Damage off the sword's own BladeHitbox (Sword.tscn), riding the animated blade — gored only
+		# Damage off the sword's own BladeHitbox (sword.tscn), riding the animated blade — gored only
 		# when the thrust reaches it. Arm at the thrust (mat_stab_strike_at) and sweep for the overlap.
 		if _sword_blade_area != null and _swing_phase() >= DP.f("mat_stab_strike_at"):
 			_sword_blade_area.activate()
@@ -1189,7 +1189,7 @@ func _spawn_sword() -> void:
 	_drawing = false
 	_apply_sword_grip()
 
-	# The blade hitbox (Sword.tscn, hitbox.gd) is armed only during the ATTACK thrust (see
+	# The blade hitbox (sword.tscn, hitbox.gd) is armed only during the ATTACK thrust (see
 	# _tick_attack); off while merely carried, so brushing a drawn matador never gores the bull.
 	_sword_blade_area = _sword_node.get_node_or_null("BladeHitbox") as Hitbox
 	if _sword_blade_area != null: