Initial project setup

Scaffold xex2tractor Rust project with cargo, add MIT license, README,
and XEX2 file format documentation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -0,0 +1,13 @@
+# xex2tractor
+
+A tool for extracting and inspecting Xbox 360 XEX2 executable files, written in Rust.
+
+## Building
+
+```sh
+cargo build --release
+```
+
+## License
+
+This project is licensed under the MIT License. See [LICENSE](LICENSE) for details.