Add 4x SAC cascade to model card

README.md

@@ -40,8 +40,10 @@ Lexer1/VSSR/
 │   ├── sunet_sagittal_8x.pth     ← Single-view SUNet baseline
 │   ├── sunet_axial_8x.pth
 │   └── sunet_coronal_8x.pth
-└── cascades_8x/
-    └── SAC_final.pth             ← Best cascade (PSNR 31.28 dB on IXI 8×)
+├── cascades_8x/
+│   └── SAC_final.pth             ← Best cascade 8× (PSNR 31.28 dB on IXI)
+└── cascades_4x/
+    └── SAC_final.pth             ← Best cascade 4×
 ```
 
 ### Download
@@ -49,7 +51,7 @@ Lexer1/VSSR/
 ```python
 from huggingface_hub import hf_hub_download
 
-path = hf_hub_download(repo_id="Lexer1/VSSR", filename="vssr_stage3_coronal.pth")
+path = hf_hub_download(repo_id="Lexer1/VSSR", filename="cascades_8x/SAC_final.pth")
 ```
 
 Or download all weights at once: