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>

tests/core/node-catalog.test.ts

@@ -609,6 +609,28 @@ const CASES: Record<string, Case[]> = {
     },
     { name: 'no object is on no layer', inputs: { object: null }, outputs: { name: '', number: -1 } },
   ],
+  RenderLayerOf: [
+    {
+      name: 'names the render layer the context says the object is drawn on (#305)',
+      inputs: { object: fakeEntity('Coin') },
+      context: { renderLayerOf: (target) => (target.name === 'Coin' ? 1 : null) },
+      lookup: { ...NO_LOOKUP, renderLayers: () => ['Default', 'UI'] },
+      outputs: { name: 'UI', number: 1 },
+    },
+    {
+      name: 'a render layer the project has not named goes by its number',
+      inputs: { object: fakeEntity('Coin') },
+      context: { renderLayerOf: () => 3 },
+      lookup: { ...NO_LOOKUP, renderLayers: () => ['Default'] },
+      outputs: { name: 'Layer 3', number: 3 },
+    },
+    {
+      name: 'an object that is not drawn is on no render layer',
+      inputs: { object: fakeEntity('Cam') },
+      outputs: { name: '', number: -1 },
+    },
+    { name: 'no object is on no render layer', inputs: { object: null }, outputs: { name: '', number: -1 } },
+  ],
   ObjectsByName: [
     {
       name: 'every object so named, in scene order',