fix(pets): use preferWebGLVersion:1 for cat canvas to avoid context conflicts

Cat gets its own canvas with WebGL1 context (Kira uses WebGL2 by default).
Different GL versions don't share buffers, so no bindBuffer spam.
Cat now renders in the PetZone section of the right sidebar where it belongs.
Removed all shared-context onAppReady plumbing.

frontend/src/components/KiraAvatar.tsx

@@ -7,7 +7,6 @@ interface Props {
   outfit: string;
   accessory: string | null;
   onTalkToggle: () => void;
-  onAppReady?: (app: any) => void;
 }
 
 type ExpressionName = 'Normal' | 'Smile' | 'Sad' | 'Angry' | 'Surprised' | 'Blushing';
@@ -83,7 +82,6 @@ export default function KiraAvatar(props: Props) {
         app.stage.addChild(model as any);
         (model as any).isInteractive = () => false;
         if (!mounted) return;
-        if (props.onAppReady) props.onAppReady(app);
 
         try {
           textureRef.current = {