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/ceil.rs

@@ -0,0 +1,21 @@
+use super::*;
+use burn_tensor::TensorData;
+
+#[test]
+fn should_diff_ceil() {
+    let data = TensorData::from([
+        [-1.9751, 0.0714, 0.0643, 0.2406],
+        [-1.3172, 0.1252, -0.1119, -0.0127],
+    ]);
+    let device = Default::default();
+    let tensor_1 = TestAutodiffTensor::<2>::from_data(data, &device).require_grad();
+    let tensor_2 = tensor_1.clone().ceil();
+    let grads = tensor_2.backward();
+
+    let grad_1 = tensor_1.grad(&grads).unwrap();
+
+    grad_1.to_data().assert_eq(
+        &TensorData::from([[0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0]]),
+        false,
+    );
+}