Re-enable @spaces.GPU decorators for persistent GPU

HuggingFace Spaces requires @spaces.GPU decorators even with
persistent GPU hardware, but we should NOT call zero.startup().

Changes:
- Re-enabled @spaces.GPU decorators on all three functions
- Added back spaces>=0.28.3 to requirements.txt
- Kept zero.startup() commented out (critical for persistent GPU)
- Models still load on CUDA (args.device), not CPU

This allows persistent GPU to work without ZeroGPU offloading errors.

gradio_app.py

@@ -269,8 +269,7 @@ height="{height}" width="100%" frameborder="0"></iframe>'
         </div>
     """
 
-# Disabled ZeroGPU due to offloading errors with large models
-# @spaces.GPU(duration=60)
+@spaces.GPU(duration=60)
 def _gen_shape(
     caption=None,
     image=None,
@@ -379,8 +378,7 @@ def _gen_shape(
     main_image = image if not MV_MODE else image['front']
     return mesh, main_image, save_folder, stats, seed
 
-# Disabled ZeroGPU due to offloading errors with large models
-# @spaces.GPU(duration=180)
+@spaces.GPU(duration=180)
 def generation_all(
     caption=None,
     image=None,
@@ -462,8 +460,7 @@ def generation_all(
         seed,
     )
 
-# Disabled ZeroGPU due to offloading errors with large models
-# @spaces.GPU(duration=60)
+@spaces.GPU(duration=60)
 def shape_generation(
     caption=None,
     image=None,

requirements.txt

@@ -5,7 +5,7 @@
 --extra-index-url https://download.blender.org/pypi/
 
 # Hugging Face Spaces Support
-# spaces>=0.28.3  # Disabled: ZeroGPU causes offloading errors with large models
+spaces>=0.28.3  # Required for @spaces.GPU decorators on persistent GPU
 
 # Build Tools
 ninja==1.11.1.1