fix(client): remove ALPHA output from toon shaders — fixes depth sorting

Writing ALPHA caused Godot to treat all meshes as transparent, breaking
per-pixel depth testing. Hair clipped through the head, clothing through
the body — all caused by object-level depth sorting instead of z-buffer.
Removing ALPHA makes everything opaque with correct depth behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/assets/characters/shaders/toon.gdshader

@@ -12,5 +12,4 @@ void fragment() {
 	float toon = step(shadow_threshold, ndl);
 	vec3 color = mix(shadow_color.rgb, base_color.rgb, toon);
 	ALBEDO = color;
-	ALPHA = base_color.a;
 }

client/assets/characters/shaders/toon_masked.gdshader

@@ -28,5 +28,4 @@ void fragment() {
 	vec3 color = base * mix(1.0 - shadow_strength, 1.0, toon);
 
 	ALBEDO = color;
-	ALPHA = original.a * tint_color.a;
 }