chore(skills+remotion): add flat-artist skill bundle; register 3D templates

- .claude/skills/flat-artist: the bundled FlatRender template-creation suite
  (orchestrator + 16 sub-skills + design/motion R&D), mirrors the Gitea AISkills repo.
- services/remotion Root.tsx/templates.tsx: register the 3D templates + Three3DTest.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/remotion/src/Root.tsx

@@ -113,13 +113,16 @@ export const RemotionRoot: React.FC = () => {
         height={720}
       />
 
-      {/* Branded templates — each registered in all three aspects. */}
+      {/* Branded templates — each registered in all three aspects. A template may
+          supply a dedicated component per aspect (componentsByAspect) when its
+          design differs structurally; otherwise the shared `component` adapts
+          responsively. */}
       {TEMPLATES.flatMap((tpl) =>
         ASPECTS.map((a) => (
           <Composition
             key={`${tpl.id}-${a.id}`}
             id={`${tpl.id}-${a.id}`}
-            component={tpl.component}
+            component={tpl.componentsByAspect?.[a.id] ?? tpl.component}
             durationInFrames={Math.round(FPS * tpl.durationSec)}
             fps={FPS}
             width={a.width}