fix: use render=False on regen buttons to suppress Gradio 5 SSR 'Too many arguments' error

gr.Button(visible=False) renders a DOM element that Gradio's SSR validator
counts when checking event argument cardinality, causing 'Too many arguments'
warnings at startup and breaking output delivery for the Generate button.

render=False removes the button from the Svelte component tree entirely while
keeping the event handler registered in gradio_config.dependencies (required
for the JS api_name -> fn_index lookup used by the queue/join regen calls).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -1337,7 +1337,7 @@ def _register_regen_handlers(tab_prefix, model_key, regen_seg_tb, regen_state_tb
     btns     = []
     for _i in range(MAX_SLOTS):
         _slot_id = f"{tab_prefix}_{_i}"
-        _btn = gr.Button(visible=False, elem_id=f"regen_btn_{_slot_id}")
+        _btn = gr.Button(render=False, elem_id=f"regen_btn_{_slot_id}")
         btns.append(_btn)
         print(f"[startup] registering regen handler for slot {_slot_id}")