Fix UI layout: move hidden regen textboxes into invisible gr.Group

visible=False on gr.Textbox inside a Column still renders empty DOM
blocks that break the layout. Wrapping them in gr.Group(visible=False)
collapses the entire group with zero visual footprint.

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

app.py

@@ -1762,9 +1762,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     taro_cf_db   = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="taro_cf_db")
                     taro_samples    = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
                     taro_btn        = gr.Button("Generate", variant="primary")
-                    # Hidden regen plumbing — do NOT remove (used as typed inputs for regen handlers)
-                    taro_regen_seg  = gr.Textbox(value="0", visible=False, elem_id="taro_regen_seg")
-                    taro_regen_state = gr.Textbox(value="", visible=False, elem_id="taro_regen_state")
+
+                with gr.Group(visible=False):
+                    # Hidden regen plumbing — zero DOM footprint, do NOT remove
+                    taro_regen_seg   = gr.Textbox(value="0", elem_id="taro_regen_seg")
+                    taro_regen_state = gr.Textbox(value="", elem_id="taro_regen_state")
 
                 with gr.Column():
                     (taro_slot_grps, taro_slot_vids,
@@ -1868,9 +1870,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     mma_cf_db    = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="mma_cf_db")
                     mma_samples     = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
                     mma_btn         = gr.Button("Generate", variant="primary")
-                    # Hidden regen plumbing
-                    mma_regen_seg   = gr.Textbox(value="0", visible=False, elem_id="mma_regen_seg")
-                    mma_regen_state = gr.Textbox(value="", visible=False, elem_id="mma_regen_state")
+
+                with gr.Group(visible=False):
+                    # Hidden regen plumbing — zero DOM footprint, do NOT remove
+                    mma_regen_seg   = gr.Textbox(value="0", elem_id="mma_regen_seg")
+                    mma_regen_state = gr.Textbox(value="", elem_id="mma_regen_state")
 
                 with gr.Column():
                     (mma_slot_grps, mma_slot_vids,
@@ -1958,9 +1962,11 @@ with gr.Blocks(title="Generate Audio for Video", css=_SLOT_CSS, js=_GLOBAL_JS) a
                     hf_cf_db    = gr.Textbox(label="Crossfade Boost (dB)", value="3", elem_id="hf_cf_db")
                     hf_samples      = gr.Slider(label="Generations", minimum=1, maximum=MAX_SLOTS, value=1, step=1)
                     hf_btn          = gr.Button("Generate", variant="primary")
-                    # Hidden regen plumbing
-                    hf_regen_seg    = gr.Textbox(value="0", visible=False, elem_id="hf_regen_seg")
-                    hf_regen_state  = gr.Textbox(value="", visible=False, elem_id="hf_regen_state")
+
+                with gr.Group(visible=False):
+                    # Hidden regen plumbing — zero DOM footprint, do NOT remove
+                    hf_regen_seg    = gr.Textbox(value="0", elem_id="hf_regen_seg")
+                    hf_regen_state  = gr.Textbox(value="", elem_id="hf_regen_state")
 
                 with gr.Column():
                     (hf_slot_grps, hf_slot_vids,