Add toon shader with outline for pose icon stage

Cel-shaded white body with tinted shadow band plus inverted-hull
clip-space outline (constant screen width, works in deferred via
SRPDefaultUnlit). Key light added to the Pose Icon scene, material
wired to the Paintman.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/Shaders/PoseIconToon.shader

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+// Minimal cel/toon shader with an inverted-hull outline for the Pose Icon stage
+// (icon screenshots of the staged Paintman). Deliberately NOT a URP/Lit clone:
+// the stage is a controlled studio setup, so main-light cel banding + ambient is
+// all the lighting it needs. Outline runs as a second pass (SRPDefaultUnlit, so
+// URP renders it without a Render Feature); width is screen-space (pixel-ish)
+// and distance-independent for consistent icon thickness.
+Shader "Custom/PoseIconToon"
+{
+    Properties
+    {
+        [MainTexture] _BaseMap("Albedo", 2D) = "white" {}
+        [MainColor] _BaseColor("Color", Color) = (1,1,1,1)
+
+        [Header(Toon Shading)]
+        _ShadeThreshold("Shade Threshold", Range(0.0, 1.0)) = 0.5
+        _ShadeSoftness("Shade Softness", Range(0.001, 0.5)) = 0.05
+        _ShadowTint("Shadow Tint", Color) = (0.55, 0.5, 0.65, 1)
+
+        [Header(Outline)]
+        _OutlineColor("Outline Color", Color) = (0.1, 0.08, 0.2, 1)
+        _OutlineWidth("Outline Width (px at 1080p)", Range(0.0, 20.0)) = 6.0
+    }
+
+    SubShader
+    {
+        Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" "Queue" = "Geometry" }
+
+        HLSLINCLUDE
+        #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
+
+        CBUFFER_START(UnityPerMaterial)
+            float4 _BaseMap_ST;
+            half4 _BaseColor;
+            half _ShadeThreshold;
+            half _ShadeSoftness;
+            half4 _ShadowTint;
+            half4 _OutlineColor;
+            half _OutlineWidth;
+        CBUFFER_END
+        ENDHLSL
+
+        Pass
+        {
+            Name "ToonForward"
+            // UniversalForwardOnly (not UniversalForward): drawn by BOTH the Forward and the
+            // Deferred renderer (the deferred path only picks up ForwardOnly/SRPDefaultUnlit
+            // passes for materials without a GBuffer pass - plain UniversalForward is skipped).
+            Tags { "LightMode" = "UniversalForwardOnly" }
+
+            HLSLPROGRAM
+            #pragma vertex ToonVertex
+            #pragma fragment ToonFragment
+
+            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
+
+            TEXTURE2D(_BaseMap);
+            SAMPLER(sampler_BaseMap);
+
+            struct Attributes
+            {
+                float4 positionOS : POSITION;
+                float3 normalOS   : NORMAL;
+                float2 uv         : TEXCOORD0;
+            };
+
+            struct Varyings
+            {
+                float4 positionCS : SV_POSITION;
+                float2 uv         : TEXCOORD0;
+                float3 normalWS   : TEXCOORD1;
+            };
+
+            Varyings ToonVertex(Attributes input)
+            {
+                Varyings output;
+                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
+                output.normalWS = TransformObjectToWorldNormal(input.normalOS);
+                output.uv = TRANSFORM_TEX(input.uv, _BaseMap);
+                return output;
+            }
+
+            half4 ToonFragment(Varyings input) : SV_Target
+            {
+                half4 albedo = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, input.uv) * _BaseColor;
+
+                Light mainLight = GetMainLight();
+                half ndl = dot(normalize(input.normalWS), mainLight.direction) * 0.5h + 0.5h;
+                half lit = smoothstep(_ShadeThreshold - _ShadeSoftness, _ShadeThreshold + _ShadeSoftness, ndl);
+
+                half3 litColor = albedo.rgb * mainLight.color;
+                half3 shadeColor = albedo.rgb * _ShadowTint.rgb;
+                half3 ambient = albedo.rgb * SampleSH(input.normalWS) * 0.25h;
+
+                return half4(lerp(shadeColor, litColor, lit) + ambient, albedo.a);
+            }
+            ENDHLSL
+        }
+
+        Pass
+        {
+            Name "Outline"
+            Tags { "LightMode" = "SRPDefaultUnlit" }
+            Cull Front
+
+            HLSLPROGRAM
+            #pragma vertex OutlineVertex
+            #pragma fragment OutlineFragment
+
+            struct Attributes
+            {
+                float4 positionOS : POSITION;
+                float3 normalOS   : NORMAL;
+            };
+
+            struct Varyings
+            {
+                float4 positionCS : SV_POSITION;
+            };
+
+            Varyings OutlineVertex(Attributes input)
+            {
+                Varyings output;
+                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
+
+                // Extrude in clip space: constant on-screen width regardless of distance.
+                float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
+                float3 normalCS = normalize(mul((float3x3)UNITY_MATRIX_VP, normalWS).xyz);
+                float2 offset = normalCS.xy * _OutlineWidth * 2.0 / 1080.0 * output.positionCS.w;
+                offset.x *= _ScreenParams.y / _ScreenParams.x; // keep width uniform on non-square aspect
+                output.positionCS.xy += offset;
+                return output;
+            }
+
+            half4 OutlineFragment(Varyings input) : SV_Target
+            {
+                return _OutlineColor;
+            }
+            ENDHLSL
+        }
+    }
+}

Assets/Shaders/PoseIconToon.shader.meta

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