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/recip.rs

@@ -0,0 +1,22 @@
+use super::*;
+use burn_tensor::TensorData;
+use burn_tensor::Tolerance;
+
+#[test]
+fn should_diff_recip() {
+    let data = TensorData::from([2.0, 5.0, 0.4]);
+
+    let tensor = TestAutodiffTensor::<1>::from_data(data, &Default::default()).require_grad();
+    let tensor_out = tensor.clone().recip();
+
+    let grads = tensor_out.backward();
+    let grad = tensor.grad(&grads).unwrap();
+
+    tensor_out
+        .into_data()
+        .assert_eq(&TensorData::from([0.5, 0.2, 2.5]), false);
+    grad.to_data().assert_approx_eq::<FloatElem>(
+        &TensorData::from([-0.25, -0.04, -6.25]),
+        Tolerance::default(),
+    );
+}