feat: add PE image decompression and extraction pipeline (M5)

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>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "xex2tractor"
-version = "0.4.0"
+version = "0.5.0"
 edition = "2024"
 description = "A tool for extracting and inspecting Xbox 360 XEX2 executable files"
 license = "MIT"
@@ -9,3 +9,4 @@ license = "MIT"
 aes = "0.8.4"
 cbc = "0.1.2"
 clap = { version = "4.6.0", features = ["derive"] }
+lzxd = "0.2.6"