Implement full decrypt + decompress pipeline for XEX2 PE extraction:
- decompress.rs: None, Basic (zero-fill), and Normal (LZX) decompression
- extract.rs: orchestrates decryption then decompression
- Wire up CLI extract command to write PE files
- LZX decompression via lzxd crate with per-frame chunk processing
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
