Fix regen duration functions: add slot_id=None param to match regen function signatures

@spaces.GPU(duration=fn) passes all args to the duration function,
so it must accept the same signature as the decorated function.
All three regen functions take slot_id as the last arg.

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

app.py

@@ -845,7 +845,7 @@ def _splice_and_save(new_wav, seg_idx, meta, slot_id):
 
 def _taro_regen_duration(video_file, seg_idx, seg_meta_json,
                          seed_val, cfg_scale, num_steps, mode,
-                         crossfade_s, crossfade_db):
+                         crossfade_s, crossfade_db, slot_id=None):
     secs   = int(num_steps) * TARO_SECS_PER_STEP + TARO_LOAD_OVERHEAD
     result = min(GPU_DURATION_CAP, max(60, int(secs)))
     print(f"[duration] TARO regen: 1 seg × {int(num_steps)} steps → {secs:.0f}s → capped {result}s")
@@ -920,7 +920,7 @@ def regen_taro_segment(video_file, seg_idx, seg_meta_json,
 
 def _mmaudio_regen_duration(video_file, seg_idx, seg_meta_json,
                              prompt, negative_prompt, seed_val,
-                             cfg_strength, num_steps, crossfade_s, crossfade_db):
+                             cfg_strength, num_steps, crossfade_s, crossfade_db, slot_id=None):
     secs   = int(num_steps) * MMAUDIO_SECS_PER_STEP + MMAUDIO_LOAD_OVERHEAD
     result = min(GPU_DURATION_CAP, max(60, int(secs)))
     print(f"[duration] MMAudio regen: 1 seg × {int(num_steps)} steps → {secs:.0f}s → capped {result}s")
@@ -1010,7 +1010,7 @@ def regen_mmaudio_segment(video_file, seg_idx, seg_meta_json,
 def _hunyuan_regen_duration(video_file, seg_idx, seg_meta_json,
                              prompt, negative_prompt, seed_val,
                              guidance_scale, num_steps, model_size,
-                             crossfade_s, crossfade_db):
+                             crossfade_s, crossfade_db, slot_id=None):
     secs   = int(num_steps) * HUNYUAN_SECS_PER_STEP + HUNYUAN_LOAD_OVERHEAD
     result = min(GPU_DURATION_CAP, max(60, int(secs)))
     print(f"[duration] HunyuanFoley regen: 1 seg × {int(num_steps)} steps → {secs:.0f}s → capped {result}s")