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/GraphCanvas.ts

@@ -28,6 +28,7 @@ import {
 } from '../../core/graph';
 import type { GraphAsset } from '../../core/model/Asset';
 import { graphLookup } from '../../core/model/graphLookup';
+import { shaderLibrary } from '../../viewport/ShaderLibrary';
 import { findAsset, findGraphAsset } from '../../core/model/Project';
 import { type Trace, TRACE_FADE } from '../../runtime/systems/BehaviorSystem';
 import { beadsInFlight, launchBead } from './beads';
@@ -218,6 +219,8 @@ export class GraphCanvas extends Widget {
     }
     const seen = new Set<string>();
     const lookup = graphLookup(this.state.project);
+    // A shader node's problem is the compiler's, not a call's.
+    const shaderProblems = asset.type === 'shader' ? shaderLibrary.buildFor(asset).problems : null;
     for (const node of asset.graph.nodes) {
       const def = resolveDef(node, asset.graph, lookup);
       if (!def) continue;
@@ -230,7 +233,10 @@ export class GraphCanvas extends Widget {
         this.views.set(node.id, view);
         this.nodeLayer.addChild(view);
       }
-      view.sync(node, asset.graph, this.state.project, def, callProblem(node, lookup, asset.id));
+      const problem = shaderProblems
+        ? (shaderProblems[node.id] ?? null)
+        : callProblem(node, lookup, asset.id);
+      view.sync(node, asset.graph, this.state.project, def, problem);
     }
     for (const [id, view] of this.views) {
       if (!seen.has(id)) {