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

Cargo.toml

@@ -8,7 +8,7 @@ clap = { version = "4.0", features = ["derive"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 anyhow = "1.0"
-stablediffusion = { path = "../stable-diffusion-burn" }
+stablediffusion = { path = "./crates/stable-diffusion-burn" }
 burn = "0.14.0"
 burn-autodiff = "0.14.0"
 burn-ndarray = "0.14.0"