Revert to gradio 6.22.0

Pinning 6.5.1 to match the reference Space made things worse, not better: on
the deployed Space the whole page dies with a svelte effect_orphan error --
no viewer canvas mounts and the episode list never populates. On 6.22.0 the
page works and the viewer mounts; only the viewer itself is unreliable.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -4,7 +4,7 @@ emoji: 🎬
 colorFrom: green
 colorTo: purple
 sdk: gradio
-sdk_version: 6.5.1
+sdk_version: 6.22.0
 python_version: '3.12'
 app_file: app.py
 pinned: false

requirements.txt

@@ -1,4 +1,4 @@
-gradio==6.5.1
+gradio==6.22.0
 gradio_rerun==0.35.0
 huggingface_hub>=0.28
 numpy