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/debugHook.ts

@@ -269,6 +269,19 @@ export function installDebugHook(app: Application, state: EditorState, editor: E
       center: () => centreOf(editor.stateMachineEditor.canvas),
       snapping: () => editor.stateMachineEditor.canvas.snapEnabled,
     },
+    shader: {
+      current: () => editor.shaderEditor.currentAssetId,
+      pickerAt: () => centreOf(editor.shaderEditor.picker),
+      info: () => editor.shaderEditor.shownInfo,
+      nodeAt: (nodeId: string) => editor.shaderEditor.canvas.nodeGlobal(nodeId),
+      nodeLabel: (nodeId: string) => editor.shaderEditor.canvas.nodeLabel(nodeId),
+      nodeRect: (nodeId: string) => editor.shaderEditor.canvas.nodeRect(nodeId),
+      nodeProblem: (nodeId: string) => editor.shaderEditor.canvas.nodeProblem(nodeId),
+      canvasRect: () => editor.shaderEditor.canvas.canvasRect(),
+      emptySpot: () => editor.shaderEditor.canvas.emptySpotGlobal(),
+      center: () => centreOf(editor.shaderEditor.canvas),
+      snapping: () => editor.shaderEditor.canvas.snapEnabled,
+    },
     /** The console panel: its lines as kept, its drawn height, and the divider above it. */
     console: {
       lines: () => editor.console.debugInfo().lines,