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-rl/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+authors = ["nathanielsimard <nathaniel.simard.42@gmail.com>"]
+categories = ["science"]
+description = "RL crate for the Burn framework"
+edition.workspace = true
+keywords = ["deep-learning", "machine-learning", "tensor", "pytorch", "ndarray"]
+license.workspace = true
+name = "burn-rl"
+readme.workspace = true
+repository = "https://github.com/tracel-ai/burn/tree/main/crates/burn-rl"
+documentation = "https://docs.rs/burn-rl"
+version.workspace = true
+
+[dependencies]
+burn-core = { path = "../burn-core", version = "=0.21.0-pre.2", features = [
+    "dataset",
+    "std",
+], default-features = false }
+burn-optim = { path = "../burn-optim", version = "=0.21.0-pre.2", features = [
+    "std",
+], default-features = false }
+
+derive-new.workspace = true
+log = { workspace = true }
+rand.workspace = true
+
+[dev-dependencies]
+burn-ndarray = { path = "../burn-ndarray", version = "=0.21.0-pre.2" }
+
+[lints]
+workspace = true