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-candle/README.md

@@ -0,0 +1,14 @@
+# Burn Candle Backend
+
+> **Deprecated:** This crate is deprecated as of `0.21.0-pre.2` and will be removed in a future release.
+> Please migrate to one of the actively maintained backends:
+> - **CubeCL backends** (CUDA, ROCm, Vulkan, Metal, WebGPU) for GPU acceleration
+> - **NdArray** for portable CPU execution
+> - **LibTorch** (`burn-tch`) for a mature CPU/GPU backend
+
+This crate provides a backend for [Burn](https://github.com/tracel-ai/burn) based on the [Candle](https://github.com/huggingface/candle) framework.
+
+## Feature Flags
+
+- `cuda` - Cuda GPU device (NVIDIA only)
+- `accelerate` - Accelerate framework (macOS only)