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>

README.md

@@ -18,6 +18,32 @@ Header Size:      0x00003000 (12288 bytes)
 Reserved:         0x00000000
 Security Offset:  0x00000090
 Header Count:     15
+
+=== Optional Headers (15 entries) ===
+
+[ENTRY_POINT] 0x824AB748
+[IMAGE_BASE_ADDRESS] 0x82000000
+[DEFAULT_STACK_SIZE] 0x00080000 (524288 bytes)
+[SYSTEM_FLAGS] 0x00000400 [PAL50_INCOMPATIBLE]
+
+[EXECUTION_INFO]
+  Media ID:        0x2D2E2EEB
+  Title ID:        0x535107D4
+  Version:         0.0.0.2
+  ...
+
+[FILE_FORMAT_INFO]
+  Encryption:  Normal (AES-128-CBC)
+  Compression: Normal (LZX)
+
+[STATIC_LIBRARIES] (12 libraries)
+  XAPILIB  2.0.3215.0 (Unknown(64))
+  D3D9     2.0.3215.1 (Unknown(64))
+  ...
+
+[IMPORT_LIBRARIES] (2 libraries)
+  xam.xex v2.0.4552.0 (min v2.0.4552.0) - 104 imports
+  xboxkrnl.exe v2.0.4552.0 (min v2.0.4552.0) - 294 imports
 ```
 
 ## Building