Migrate shaders to URP and add loading screen

Reworks multiple shaders and materials for URP compatibility and adds a Loading screen/scene and a few model imports. Key changes:
- Converted ProBuilder standard vertex-color shader and several particle/surface shaders to URP HLSL passes (UniversalForward, ShadowCaster, Depth, DepthNormals) preserving base texture * tint * vertex color, normal map and PBR parameters.
- Updated particle SurfaceShader_VC to a URP forward pass and simplified lighting to use URP shader library helpers.
- Updated materials (landMark, tile) to point to project textures, adjust keywords/flags (e.g. XRMotionVectorsPass, disable ShadowCaster for one), tweak tiling and base color values.
- Added a Loading screen UI (UXML, USS) and LoadingScreenController.cs plus a new Loading scene and scene metadata.
- Imported new FBX assets (T-Pose, Untitled) and updated Editor build settings / project settings to include the new Loading scene.
These changes migrate rendering code to the Universal Render Pipeline and add a basic loading UI/scene, while updating materials and project settings accordingly.

Assets/Game Kit Controller/Shaders/laserShader.shader

@@ -1,59 +1,61 @@
-// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
-
-Shader "Custom/laserShader" {
-
+Shader "Custom/URP_LaserShader"
+{
 	Properties {
 		_MainTex ("Base", 2D) = "white" {}
 		_TintColor ("TintColor", Color) = (0.5, 0.5, 0.5, 0.5)
 	}
-	
-	CGINCLUDE
-
-		#include "UnityCG.cginc"
-
-		sampler2D _MainTex;
-		fixed4 _TintColor;
-						
-		struct v2f {
-			half4 pos : SV_POSITION;
-			half2 uv : TEXCOORD0;
-		};
-
-		v2f vert(appdata_full v) {
-			v2f o;
-			
-			o.pos = UnityObjectToClipPos (v.vertex);	
-			o.uv.xy = v.texcoord.xy;
-					
-			return o; 
-		}
-		
-		fixed4 frag( v2f i ) : COLOR {	
-			return tex2D (_MainTex, i.uv.xy) * _TintColor;
-		}
-	
-	ENDCG
-	
 	SubShader {
-		Tags { "RenderType" = "Transparent" "Queue" = "Transparent"}
+		Tags { "RenderType" = "Transparent" "Queue" = "Transparent" }
+		LOD 100
 		Cull Off
-		Lighting Off
 		ZWrite Off
-		Fog { Mode Off }
 		Blend SrcAlpha One
-		
-	Pass {
-	
-		CGPROGRAM
-		
-		#pragma vertex vert
-		#pragma fragment frag
-		#pragma fragmentoption ARB_precision_hint_fastest 
-		
-		ENDCG
-		 
+
+		Pass {
+			Name "FORWARD"
+			Tags { "LightMode" = "UniversalForward" }
+
+			HLSLPROGRAM
+			#pragma vertex vert
+			#pragma fragment frag
+			#pragma multi_compile_fog
+			#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
+
+			struct Attributes {
+				float4 positionOS : POSITION;
+				float2 uv         : TEXCOORD0;
+			};
+
+			   struct Varyings {
+				   float4 positionHCS : SV_POSITION;
+				   float2 uv          : TEXCOORD0;
+				   float fogFactor    : TEXCOORD1;
+			   };
+
+			CBUFFER_START(UnityPerMaterial)
+				float4 _TintColor;
+			CBUFFER_END
+
+			TEXTURE2D(_MainTex); SAMPLER(sampler_MainTex);
+
+			Varyings vert(Attributes IN)
+			{
+				Varyings OUT;
+				OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);
+				OUT.uv = IN.uv;
+			OUT.fogFactor = ComputeFogFactor(OUT.positionHCS.z / OUT.positionHCS.w);
+				return OUT;
+			}
+
+			float4 frag(Varyings IN) : SV_Target
+			{
+				float4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, IN.uv);
+				float4 col = tex * _TintColor;
+			col.rgb = MixFog(col.rgb, IN.fogFactor);
+				return col;
+			}
+			ENDHLSL
 		}
-				
-	} 
+	}
 	FallBack Off
 }