feat: parse and display all optional headers (M2)

Implement parsing for all 15 optional header types found in XEX2 files:
inline values (entry point, base address, stack size, system flags),
fixed-size structures (execution info, file format, TLS, game ratings,
LAN key, checksum/timestamp), and variable-size structures (static
libraries, import libraries, resource info, original PE name, Xbox 360
logo). Add comprehensive unit and integration tests.

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

tests/integration.rs

@@ -1,10 +1,13 @@
 use xex2tractor::header::{ModuleFlags, XEX2_MAGIC};
+use xex2tractor::optional::{CompressionType, EncryptionType, SystemFlags};
 
 fn sample_data() -> Vec<u8> {
     let path = format!("{}/tests/data/default.xex", env!("CARGO_MANIFEST_DIR"));
     std::fs::read(&path).expect("sample file should exist at tests/data/default.xex")
 }
 
+// ── Header tests ──────────────────────────────────────────────────────────────
+
 #[test]
 fn test_full_parse() {
     let data = sample_data();
@@ -27,11 +30,98 @@ fn test_parse_empty_file() {
 #[test]
 fn test_parse_invalid_magic() {
     let mut data = sample_data();
-    // Corrupt the magic bytes
     data[0] = 0x00;
     assert!(xex2tractor::parse(&data).is_err());
 }
 
+// ── Optional header tests ─────────────────────────────────────────────────────
+
+#[test]
+fn test_optional_headers_all_present() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let opt = &xex.optional_headers;
+
+    // All 15 entries should be parsed
+    assert_eq!(opt.entries.len(), 15);
+
+    // Verify presence of all expected headers
+    assert!(opt.entry_point.is_some());
+    assert!(opt.image_base_address.is_some());
+    assert!(opt.default_stack_size.is_some());
+    assert!(opt.system_flags.is_some());
+    assert!(opt.execution_info.is_some());
+    assert!(opt.file_format_info.is_some());
+    assert!(opt.checksum_timestamp.is_some());
+    assert!(opt.original_pe_name.is_some());
+    assert!(opt.tls_info.is_some());
+    assert!(opt.static_libraries.is_some());
+    assert!(opt.import_libraries.is_some());
+    assert!(opt.resource_info.is_some());
+    assert!(opt.game_ratings.is_some());
+    assert!(opt.lan_key.is_some());
+    assert!(opt.xbox360_logo_size.is_some());
+}
+
+#[test]
+fn test_optional_inline_values() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let opt = &xex.optional_headers;
+
+    assert_eq!(opt.entry_point.unwrap(), 0x824AB748);
+    assert_eq!(opt.image_base_address.unwrap(), 0x82000000);
+    assert_eq!(opt.default_stack_size.unwrap(), 0x00080000);
+    assert_eq!(opt.system_flags.unwrap(), SystemFlags(0x00000400));
+}
+
+#[test]
+fn test_optional_execution_info() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let exec = xex.optional_headers.execution_info.as_ref().unwrap();
+
+    assert_eq!(exec.title_id, 0x535107D4);
+    assert_eq!(exec.media_id, 0x2D2E2EEB);
+}
+
+#[test]
+fn test_optional_file_format() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let fmt = xex.optional_headers.file_format_info.as_ref().unwrap();
+
+    assert_eq!(fmt.encryption_type, EncryptionType::Normal);
+    assert_eq!(fmt.compression_type, CompressionType::Normal);
+}
+
+#[test]
+fn test_optional_static_libraries() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let libs = xex.optional_headers.static_libraries.as_ref().unwrap();
+
+    assert_eq!(libs.len(), 12);
+    // Verify first and a few known libraries
+    assert_eq!(libs[0].name, "XAPILIB");
+    assert_eq!(libs[1].name, "D3D9");
+    assert_eq!(libs[3].name, "XBOXKRNL");
+}
+
+#[test]
+fn test_optional_import_libraries() {
+    let data = sample_data();
+    let xex = xex2tractor::parse(&data).unwrap();
+    let imports = xex.optional_headers.import_libraries.as_ref().unwrap();
+
+    assert_eq!(imports.string_table.len(), 2);
+    assert_eq!(imports.string_table[0], "xam.xex");
+    assert_eq!(imports.string_table[1], "xboxkrnl.exe");
+    assert!(!imports.libraries.is_empty());
+}
+
+// ── CLI tests ─────────────────────────────────────────────────────────────────
+
 #[test]
 fn test_cli_runs_with_sample() {
     let path = format!("{}/tests/data/default.xex", env!("CARGO_MANIFEST_DIR"));
@@ -42,10 +132,28 @@ fn test_cli_runs_with_sample() {
 
     assert!(output.status.success(), "CLI should exit successfully");
     let stdout = String::from_utf8_lossy(&output.stdout);
-    assert!(stdout.contains("XEX2 Header"), "should display header section");
-    assert!(stdout.contains("0x58455832"), "should display magic value");
-    assert!(stdout.contains("TITLE"), "should display module flag name");
-    assert!(stdout.contains("Header Count:     15"), "should show 15 headers");
+
+    // Header section
+    assert!(stdout.contains("XEX2 Header"));
+    assert!(stdout.contains("0x58455832"));
+    assert!(stdout.contains("TITLE"));
+    assert!(stdout.contains("Header Count:     15"));
+
+    // Optional headers section
+    assert!(stdout.contains("Optional Headers (15 entries)"));
+    assert!(stdout.contains("[ENTRY_POINT] 0x824AB748"));
+    assert!(stdout.contains("[IMAGE_BASE_ADDRESS] 0x82000000"));
+    assert!(stdout.contains("EXECUTION_INFO"));
+    assert!(stdout.contains("0x535107D4")); // title ID
+    assert!(stdout.contains("FILE_FORMAT_INFO"));
+    assert!(stdout.contains("Normal (AES-128-CBC)"));
+    assert!(stdout.contains("Normal (LZX)"));
+    assert!(stdout.contains("STATIC_LIBRARIES"));
+    assert!(stdout.contains("XAPILIB"));
+    assert!(stdout.contains("IMPORT_LIBRARIES"));
+    assert!(stdout.contains("xboxkrnl.exe"));
+    assert!(stdout.contains("default.pe")); // original PE name
+    assert!(stdout.contains("PAL50_INCOMPATIBLE")); // system flags
 }
 
 #[test]
@@ -54,9 +162,9 @@ fn test_cli_no_args() {
         .output()
         .expect("failed to run xex2tractor");
 
-    assert!(!output.status.success(), "CLI should fail without args");
+    assert!(!output.status.success());
     let stderr = String::from_utf8_lossy(&output.stderr);
-    assert!(stderr.contains("Usage"), "should print usage message");
+    assert!(stderr.contains("Usage"));
 }
 
 #[test]
@@ -66,5 +174,5 @@ fn test_cli_missing_file() {
         .output()
         .expect("failed to run xex2tractor");
 
-    assert!(!output.status.success(), "CLI should fail with missing file");
+    assert!(!output.status.success());
 }