Fix ZeroGPU proxy token expiry: single GPU allocation for full pipeline

Individual @spaces.GPU decorators on each baking stage caused the proxy
token (tied to the original Gradio request) to expire by the time material
and AO baking ran. Fix: remove per-stage decorators and put a single
@spaces.GPU(duration=600) on run_post_process so all baking happens within
one uninterrupted GPU allocation.

app.py

@@ -239,6 +239,7 @@ def handle_generate(images, model, quality, seed, _steps, _octree, tex_size, _sy
     yield from generate_hunyuan(images, quality, int(seed), int(tex_size), do_rembg=bool(do_rembg))
 
 
+@spaces.GPU(duration=600)
 def run_post_process(
     do_repair, do_cleanup, do_decimate, target_faces,
     do_symmetry, do_unwrap, do_normal_bake, normal_format,

src/stages/stage2_bake_normal.py

@@ -76,7 +76,7 @@ def _dilate(img: np.ndarray, mask: np.ndarray, iterations: int = 8) -> np.ndarra
 # GPU bake
 # ---------------------------------------------------------------------------
 
-@spaces.GPU(duration=120)
+
 def bake_normal_map(
     high_poly_path: Path,
     unwrapped_glb_path: Path,