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>

tests/core/enabled.test.ts

@@ -44,7 +44,7 @@ describe('the enabled switch', () => {
     const f = makeSpriteScene();
     const { project, stack, sceneId, spriteId, object } = f;
     const box = place(f, spriteId, { x: 0, y: 0 });
-    expect(resolveSceneObjectProps(findAsset(project, spriteId)!, object(box)).enabled).toBe(true);
+    expect(resolveSceneObjectProps(project, findAsset(project, spriteId)!, object(box)).enabled).toBe(true);
 
     // Switching an instance off is an ordinary override – and survives a round trip.
     stack.execute(new SetOverrideCommand(sceneId, box, 'enabled', false));