Let a shader declare a color the sprite sets (#298)

A shader could only ask its sprites for numbers. A tint, an outline
colour or a glow colour had to be built from three Property nodes.

- New node Color property next to Property: Name and Default (a
  colour, white unless picked), output `color`. It becomes a colour
  row below the Shader dropdown and a vec3 uniform in the program.
- Number and colour properties share one set of names. A clash is
  the existing "Another property is named" problem.
- Like Color it cannot feed the Vertex output.
- Placed from the palette it is called tint, then tint2.
- The preview in the Shader tab shows a colour field for it. Like
  the sliders it starts at the sprite's value and never writes into
  the project.
- `declaredRows` takes the row builder, so the particle graph keeps
  its number rows unchanged.

Tests:
- Gate: 222 files, 3452 tests (3445 + 7)
- e2e 28: 89 checks (28l-v: default colour drawn, then the colour
  the sprite sets)
- e2e total 1704, counted (1703 + 1)

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

src/editor/graph/paletteEntries.ts

@@ -27,7 +27,12 @@ import {
   PROPERTY_NAME_PARAM as PARTICLE_NAME_PARAM,
   propertyNameOf,
 } from '../../core/properties/particles';
-import { nextPropertyName, PROPERTY_NAME_PARAM, SHADER_PROPERTY } from '../../core/properties/shaders';
+import {
+  nextPropertyName,
+  PROPERTY_NAME_PARAM,
+  SHADER_COLOR_PROPERTY,
+  SHADER_PROPERTY,
+} from '../../core/properties/shaders';
 import { nextParticlePropertyName, PARTICLE_NODES, PARTICLE_OUTPUT } from '../../core/particles/nodes';
 import { SHADER_NODES, SHADER_OUTPUT, SHADER_VERTEX_OUTPUT } from '../../core/shader/nodes';
 
@@ -99,7 +104,11 @@ export function paletteEntries(project: Project, asset: GraphAsset): PaletteEntr
     const once = [SHADER_OUTPUT, SHADER_VERTEX_OUTPUT];
     return SHADER_NODES.filter((def) => !once.includes(def.type) || !placed.has(def.type)).map((def) => {
       const params: PropertyBag =
-        def.type === SHADER_PROPERTY ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph) } : {};
+        def.type === SHADER_PROPERTY
+          ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph) }
+          : def.type === SHADER_COLOR_PROPERTY
+            ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph, 'tint') }
+            : {};
       return { id: def.type, hint: def.category, def, params };
     });
   }