feat: parse and display XEX2 main header (M1)

Implement XEX2 main header parsing with module flag decoding.
Add error handling, big-endian read utilities, CLI entry point,
and comprehensive unit + integration tests against a sample file.

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

src/lib.rs

@@ -0,0 +1,32 @@
+//! # xex2tractor
+//!
+//! A library for parsing Xbox 360 XEX2 executable files.
+//!
+//! XEX2 is the executable format used by the Xbox 360 console. This crate
+//! provides types and functions to parse the binary format and extract
+//! structured information from XEX2 files.
+
+pub mod display;
+pub mod error;
+pub mod header;
+pub mod util;
+
+use error::Result;
+use header::Xex2Header;
+
+/// A parsed XEX2 file containing all extracted structures.
+#[derive(Debug)]
+pub struct Xex2File {
+    /// The main XEX2 header (magic, flags, sizes, offsets).
+    pub header: Xex2Header,
+}
+
+/// Parses an XEX2 file from a byte slice.
+///
+/// The `data` slice should contain the entire XEX2 file contents.
+/// Returns a [`Xex2File`] with all successfully parsed structures.
+pub fn parse(data: &[u8]) -> Result<Xex2File> {
+    let header = header::parse_header(data)?;
+
+    Ok(Xex2File { header })
+}