fix: Taila reads like her source render — no white rim, matte hair

Two separate causes behind "too glossy with a thin white outline":

1. The model carries its OWN cel line-work as extra, UNTEXTURED surfaces —
   an inverted-hull outline shell plus eye-line/highlight cards (Taila names
   them FullBlack / EyesFullBlack / EyesInvL / EyesHL). They are authored to
   read as flat black, but the glTF import hands them a default near-white
   albedo, and apply_toon_recursive then LIT them. That is the thin white
   rim: a pale, toon-shaded outline shell tracing every hair strand. They now
   render unshaded flat ink (flat white for the "HL" highlight card).

2. The skin textures already have cel shading painted in. Stacking our hard
   3-tone break on top produced a bright stripe that slid across the hair as
   the camera moved — the "gloss". Characters now get a soft terminator and
   an almost-invisible second step, so the painted shading carries the form.

Both live in a new LevelMaterials.apply_character_look(), called only for
imported character GLBs, so props and level geometry keep exactly the crisp
banding they were calibrated with. The one shared change is that the toon
shader's second-step darkness is now the mid_tone uniform, defaulting to the
0.82 that was hardcoded — no change for existing callers.

Character shadow tint (0.64, 0.56, 0.72) is measured off the Sketchfab
reference render rather than guessed: sampling the hair there, shadow/midtone
lands near (0.63, 0.53, 0.70). Green drops hardest, which is what keeps
copper hair copper instead of washing it to brown.

debug/character_look_capture.gd renders the raw import beside our treatment
under matched lighting — the comparison this was tuned against.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

assets/shaders/toon.gdshader

@@ -15,6 +15,11 @@ uniform float triplanar_tile = 2.0;      // world units per texture tile
 uniform float band_edge : hint_range(-1.0, 1.0) = 0.05;   // NdotL where light band starts
 uniform float band_softness : hint_range(0.001, 0.5) = 0.04;
 uniform float mid_band_edge : hint_range(-1.0, 1.0) = 0.55; // second, brighter band
+// How dark the mid band sits below full light. Near 1.0 the second step almost
+// disappears, which is what textures that already carry painted cel shading
+// (imported anime characters) need — a hard step on top of painted shading
+// reads as a glossy stripe sweeping across the hair.
+uniform float mid_tone : hint_range(0.0, 1.0) = 0.82;
 uniform vec4 shadow_color : source_color = vec4(0.62, 0.65, 0.78, 1.0); // cool shadow tint
 // Matte-anime defaults: zero specular (any stepped glint reads as shine
 // sweeping across hair/cloth when the camera moves), whisper of rim.
@@ -69,8 +74,8 @@ void light() {
 	float lit = ndotl * ATTENUATION;
 	float band = smoothstep(band_edge - band_softness, band_edge + band_softness, lit);
 	float mid = smoothstep(mid_band_edge - band_softness, mid_band_edge + band_softness, lit);
-	// 3 tones: shadow tint -> base band (0.82) -> full light.
-	float tone = mix(0.82, 1.0, mid);
+	// 3 tones: shadow tint -> base band (mid_tone) -> full light.
+	float tone = mix(mid_tone, 1.0, mid);
 	vec3 shade = mix(shadow_color.rgb, vec3(tone), band);
 	DIFFUSE_LIGHT += ALBEDO * LIGHT_COLOR / PI * shade;