feat: update workspace paths and enhance gitignore

- Updated stablediffusion crate path from "../stable-diffusion-burn" to "./crates/stable-diffusion-burn" for proper workspace resolution
- Enhanced .gitignore to include generated model files (.mpk, .pt, .bin, .safetensors, .ckpt) and user_data directory
- Added Cargo.lock to gitignore with appropriate comment
- Reorganized IDE files section in gitignore for better clarity
- Added newline at end of file for proper formatting

crates/stable-diffusion-burn/burn-crates/burn-backend-tests/tests/autodiff/unfold.rs

@@ -0,0 +1,18 @@
+use super::*;
+use burn_tensor::TensorData;
+
+#[test]
+fn unfold_backward_accumulates_overlaps() {
+    let device = Default::default();
+    let x = TestAutodiffTensor::<2>::from_data([[1.0, 2.0, 3.0, 4.0]], &device).require_grad();
+
+    let y = x.clone().unfold::<3, _>(1, 2, 1);
+    let loss = y.sum();
+
+    let grads = loss.backward();
+    let grad_x = x.grad(&grads).unwrap();
+
+    grad_x
+        .to_data()
+        .assert_eq(&TensorData::from([[1., 2., 2., 1.]]), false);
+}