Shader graph: Number node, a typed constant like Color (#72)

No input, one Value param (step 0.05, drawn on the node), output `value`
as a float literal via floatLiteral (2 -> 2.0, NaN -> 0.0). No uniform,
no sprite row - that is the difference to Property.

The e2e negative check for "no behavior node in the palette" now uses
Boolean as its marker, and step 28 types the palette search first
because the palette scrolls from twelve entries on.

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

src/editor/debugHook.ts

@@ -278,6 +278,7 @@ export function installDebugHook(app: Application, state: EditorState, editor: E
       nodeLabel: (nodeId: string) => editor.shaderEditor.canvas.nodeLabel(nodeId),
       nodeRect: (nodeId: string) => editor.shaderEditor.canvas.nodeRect(nodeId),
       nodeProblem: (nodeId: string) => editor.shaderEditor.canvas.nodeProblem(nodeId),
+      nodeSettings: (nodeId: string) => editor.shaderEditor.canvas.nodeSettings(nodeId),
       canvasRect: () => editor.shaderEditor.canvas.canvasRect(),
       emptySpot: () => editor.shaderEditor.canvas.emptySpotGlobal(),
       center: () => centreOf(editor.shaderEditor.canvas),