fix: outfit texture swap via internalModel.textures array

model.internalModel.coreModel.setTexture() expects a raw WebGL
texture, not a PixiJS Texture. Instead, set the new PixiJS Texture
directly on the model's internalModel.textures[2] array. The render
loop's bindTexture() call extracts the WebGL handle from the PixiJS
BaseTexture and passes it to the Cubism core.

This eliminates the cascade of try-catch fallbacks and the
'coreModel.setTexture is not a function' TypeError.

frontend/src/components/KiraAvatar.tsx

@@ -169,19 +169,14 @@ export default function KiraAvatar(props: Props) {
 
     (async () => {
       try {
-        const { Assets, Texture } = await import('pixi.js');
+        const { Assets } = await import('pixi.js');
         const tex = await Assets.load(outfitUrl);
-        // Swap texture slot 2 (clothing layer)
-        if ((model as any).setTexture) {
-          (model as any).setTexture(2, tex);
+        // Swap texture slot 2 (clothing layer) in the model's texture array.
+        // The render loop automatically binds WebGL textures from PixiJS textures.
+        if ((model as any).internalModel?.textures) {
+          (model as any).internalModel.textures[2] = tex;
         } else {
-          // Fallback: try internal model
-          try {
-            (model.internalModel as any).setTexture(2, tex);
-          } catch {
-            // Fallback: direct core model
-            (model.internalModel.coreModel as any).setTexture(2, tex);
-          }
+          console.warn('[Outfit] cannot swap — no textures array');
         }
       } catch (e) {
         console.warn('[Outfit] texture swap failed:', e);