Add radial hero-cutout shader for third-person camera

Reveal the player when geometry sits between the orbit camera and the
character: a screen-space circular mask in a URP/Lit clone (HeroCutoutLit)
clips occluders in front of the player, depth-gated so only geometry nearer
than the hero is cut. The cutout lives outside UnityPerMaterial (SRP batcher
intact) and is a no-op when disarmed, so occluders look identical to URP/Lit.

A runtime driver (HeroCutout.cs on Main/GameManager) feeds the player's
screen position, radius, feather and depth into global shader properties and
only arms while the third-person orbit vcam is live; it disarms in
first-person, free-cam and the pause menu. Applied to the lobby walls via a
dedicated occluder material (floor left solid). Shipped but shelved for now.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scenes/Lobby.unity

@@ -184,7 +184,7 @@ MeshRenderer:
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   m_RendererPriority: 0
   m_Materials:
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+  - {fileID: 2100000, guid: 284ac320f0449154dae9b92d90f5550b, type: 2}
   m_StaticBatchInfo:
     firstSubMesh: 0
     subMeshCount: 0
@@ -296,7 +296,7 @@ MeshRenderer:
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   m_RendererPriority: 0
   m_Materials:
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@@ -408,7 +408,7 @@ MeshRenderer:
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   m_RendererPriority: 0
   m_Materials:
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   m_StaticBatchInfo:
     firstSubMesh: 0
     subMeshCount: 0
@@ -520,7 +520,7 @@ MeshRenderer:
   m_RenderingLayerMask: 1
   m_RendererPriority: 0
   m_Materials:
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   m_StaticBatchInfo:
     firstSubMesh: 0
     subMeshCount: 0
@@ -632,7 +632,7 @@ MeshRenderer:
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   m_RendererPriority: 0
   m_Materials:
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   m_StaticBatchInfo:
     firstSubMesh: 0
     subMeshCount: 0
@@ -856,7 +856,7 @@ MeshRenderer:
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   m_RendererPriority: 0
   m_Materials:
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@@ -968,7 +968,7 @@ MeshRenderer:
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   m_Materials:
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   m_StaticBatchInfo:
     firstSubMesh: 0
     subMeshCount: 0

Assets/Scenes/Main.unity

@@ -1823,6 +1823,7 @@ GameObject:
   m_Component:
   - component: {fileID: 1516578028}
   - component: {fileID: 1516578027}
+  - component: {fileID: 1516578029}
   m_Layer: 0
   m_Name: GameManager
   m_TagString: Untagged
@@ -1864,6 +1865,24 @@ Transform:
   m_Children: []
   m_Father: {fileID: 0}
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!114 &1516578029
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 1516578026}
+  m_Enabled: 0
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: c7d67030b8dcdec489471b88c35dd78b, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: Assembly-CSharp::HeroCutout
+  orbitInput: {fileID: 0}
+  modes: {fileID: 0}
+  radius: 0.3
+  feather: 0.1
+  depthBias: 0.5
+  heightOffset: 0
 --- !u!21 &1752619484
 Material:
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