feat: add unity-aligned shader contract metadata

engine/assets/builtin/shaders/forward-lit/forward-lit.shader

@@ -1,11 +1,57 @@
 {
   "name": "Builtin Forward Lit",
+  "properties": [
+    {
+      "name": "_BaseColor",
+      "displayName": "Base Color",
+      "type": "Color",
+      "defaultValue": "(1,1,1,1)",
+      "semantic": "BaseColor"
+    },
+    {
+      "name": "_MainTex",
+      "displayName": "Base Map",
+      "type": "2D",
+      "defaultValue": "white",
+      "semantic": "BaseColorTexture"
+    }
+  ],
   "passes": [
     {
       "name": "ForwardLit",
       "tags": {
         "LightMode": "ForwardBase"
       },
+      "resources": [
+        {
+          "name": "PerObjectConstants",
+          "type": "ConstantBuffer",
+          "set": 1,
+          "binding": 0,
+          "semantic": "PerObject"
+        },
+        {
+          "name": "MaterialConstants",
+          "type": "ConstantBuffer",
+          "set": 2,
+          "binding": 0,
+          "semantic": "Material"
+        },
+        {
+          "name": "BaseColorTexture",
+          "type": "Texture2D",
+          "set": 3,
+          "binding": 0,
+          "semantic": "BaseColorTexture"
+        },
+        {
+          "name": "LinearClampSampler",
+          "type": "Sampler",
+          "set": 4,
+          "binding": 0,
+          "semantic": "LinearClampSampler"
+        }
+      ],
       "variants": [
         {
           "stage": "Vertex",