Shaders draw in the sprite's own pass: a Mesh with the graph's fragment, no filter (#77)

A sprite's picture is now a Mesh (unit quad, sibling of its Graphics node, which keeps
only the hit area); a worn shader replaces Pixi's fragment in that draw, so there is no
intermediate texture and no extra render pass. Measured on the HD 630: 400 shaded
sprites hold 60 fps (was 34), 800 hold 56 (was 20).

Two Pixi facts the code leans on: a mesh's texture is bound only for Pixi's own shader,
so GraphShader.wear hands it over; and MeshPipe caches whether a mesh batches and
re-checks it only in a frame without structure changes, so switching a shader on or
off calls mesh.unload().

The console panel mirrors console.group/groupCollapsed/groupEnd and fills the %s %d
%o %c directives, so Pixi's deprecation warning shows its head, not only its stack.
E2E 12 guards against the addChild-on-Graphics warning, 28 counts shaders instead of
filters.

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

src/core/shader/compile.ts

@@ -130,14 +130,17 @@ export function compileShader(graph: Graph): ShaderBuild {
     return { compiled: null, problems, reason: first ? problems[first.id]! : 'Cannot compile' };
 
   const uniforms = shaderParamDefs(graph).map((row) => ({ name: row.key, default: row.default }));
+  // The fragment runs in the sprite's own draw (#77). `vColor` is the tint, premultiplied like the
+  // texel; it goes in before the graph, so `Texture color` is the sprite as it draws without a shader.
   const fragment = [
     'in vec2 vTextureCoord;',
+    'in vec4 vColor;',
     'out vec4 finalColor;',
     'uniform sampler2D uTexture;',
     ...uniforms.map((u) => `uniform float ${uniformName(u.name)};`),
     'void main()',
     '{',
-    '    vec4 texel = texture(uTexture, vTextureCoord);',
+    '    vec4 texel = texture(uTexture, vTextureCoord) * vColor;',
     `    vec3 ${TEXEL_COLOR.code} = texel.a > 0.0 ? texel.rgb / texel.a : texel.rgb;`,
     ...lines.map((line) => `    ${line}`),
     `    float alpha = clamp(${alpha.code}, 0.0, 1.0);`,