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/common/autodiff.rs

@@ -0,0 +1,35 @@
+// Burn autodiff tests, reusable with element types.
+
+pub use super::*;
+
+#[path = "../autodiff/mod.rs"]
+mod base;
+
+mod checkpointing {
+    pub use super::*;
+    use burn_autodiff::checkpoint::strategy::BalancedCheckpointing;
+
+    // Override type def
+    pub type TestAutodiffBackend = Autodiff<TestBackend, BalancedCheckpointing>;
+    pub type TestAutodiffTensor<const D: usize> = Tensor<TestAutodiffBackend, D>;
+
+    include!("../autodiff/mod.rs");
+}
+
+use burn_backend_tests::test_float_elem_variant;
+
+// NOTE: this currently doesn't test checkpointing with different dtypes
+test_float_elem_variant!(
+    f16,
+    burn_tensor::f16,
+    "../autodiff/mod.rs",
+    ["vulkan", "cuda", "rocm", "metal"]
+);
+
+// TODO: bf16 not yet supported on any backend for full test suite
+// test_float_elem_variant!(
+//     bf16,
+//     burn_tensor::bf16,
+//     "../autodiff/mod.rs",
+//     [] // ["cuda", "rocm"] TODO, ["vulkan"] only supports bf16 for matmul, metal/wgpu doesn't support bf16
+// );