Add a node that names the render layer of an object (#305)

The issue asked for Set render layer, Set sees and Render layer of. As
with #211, a probe showed that writing already works. A Properties
node of the object's type writes Render layer during a run, Inherit
included, and one of type Camera writes Sees. The next picture follows
both. As agreed, only Render layer of is built, and writing stays with
Properties.

- Render layer of is a data node with the input object and the outputs
  name and number. It answers the layer that holds, so an object
  without a choice of its own names its parent's.
- NodeContext.renderLayerOf answers the number with the same rule the
  drawing uses (renderLayerAlong). The new field renderLayers on
  GraphLookup brings the names to the node.
- hasRenderLayer in PropertySchema says which types are drawn.
- Decided here: for an object that is not drawn (a camera, a
  behavior, a collider) the name is empty and the number -1, as Layer
  of does without a collider.

Changing the render layer or Sees during a run had no test so far.
Three unit tests now hold the proof from the issue.

Tests:
- Gate: 231 files, 3534 tests (3526 + 8), exit 0
- e2e 6: 149 checks passed, e2e 63: 13 checks passed (+1)
- Unit: the coin moves into the overlay with Set and back with
  Inherit, a HUD container takes its sprite along, the main camera sees
  a second layer once its Sees is set, and Render layer of names the
  inherited layer, and none for a behavior
- Node catalog: four cases for Render layer of
- 63c3 moves a sprite onto UI in a Play run: the main camera no longer
  draws it, and the log reads "UI" and "1"
- Three counter-probes fail 1, 1 and 2 tests: without inheriting in
  the node, without the check for a drawn type, and without
  inheriting in the drawing
- "layer of" in the palette still finds Layer of first (6z-x)
- The e2e sum is 1731 (1730 plus 1)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/core/graph/lookup.ts

@@ -45,8 +45,8 @@ export interface StateMachine {
  * What a node may look up in the project around its graph: the behaviors it can run, the state
  * machines it can read, the curves a `Lerp` eases along (#247) and the struct types `Add item`
  * checks (#254), what a variable written by a graph is held to (#271), how long an animation is
- * (#233) and what the collision layers are called (#211). One handle, so no caller can resolve a
- * node with half of it.
+ * (#233) and what the collision and render layers are called (#211, #305). One handle, so no caller
+ * can resolve a node with half of it.
  */
 export interface GraphLookup {
   behavior(assetId: string): BehaviorProgram | null;
@@ -62,6 +62,8 @@ export interface GraphLookup {
   animation(assetId: string): AnimationClip | null;
   /** The project's collision layers by number, as `Layer of` names them (#211). */
   collisionLayers(): readonly string[];
+  /** The project's render layers by number, as `Render layer of` names them (#305). */
+  renderLayers(): readonly string[];
   /** The asset whose graph this is, `''` for none. */
   ownerOf(graph: Graph): string;
   /** What a variable of that asset declares about the structs it holds (#271); none for nothing typed. */
@@ -94,6 +96,7 @@ export const NO_LOOKUP: GraphLookup = {
   textureSize: () => null,
   animation: () => null,
   collisionLayers: () => [],
+  renderLayers: () => [],
   ownerOf: () => '',
   variableTyping: () => undefined,
 };