Shader assets: graph-built shaders, the Shader tab and sprite rows from the graph (#62)

A shader is an asset carrying a node graph (Texture color, Output, Property,
Color, Add/Subtract/Multiply/Divide, Mix, Luminance) that compiles to the GLSL
fragment of a Pixi filter. The Shader tab reuses the Behavior canvas; a sprite
wears a shader through its Shader picker, and the rows below it are the
graph's Property nodes. Property schema, resolution and deviation take the
project because a sprite's rows now live in another asset. The built-in
registry of the prototype is gone; "Adjust colors" ships as a graph in the
fixture and the three example games.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/editor/graph/NodeView.ts

@@ -51,6 +51,8 @@ export function categoryColor(category: NodeCategory): number {
       return c.categoryAction;
     case 'state':
       return c.categoryState;
+    case 'shader':
+      return c.categoryShader;
   }
 }
 
@@ -71,6 +73,8 @@ export function portColor(type: PortType): number {
       return c.portList;
     case 'struct':
       return c.portStruct;
+    case 'vec3':
+      return c.portVec3;
     case 'any':
       return c.portAny;
   }