feat: show decrypted session key in inspect output

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

src/display.rs

@@ -1,4 +1,5 @@
 /// Pretty-print formatting for parsed XEX2 structures.
+use crate::crypto;
 use crate::header::Xex2Header;
 use crate::optional::{
     format_hex_bytes, format_rating, format_timestamp, CompressionInfo, HeaderKey, OptionalHeaders,
@@ -266,6 +267,11 @@ pub fn display_security_info(security: &SecurityInfo) {
         "AES Key (encrypted):  {}",
         format_hex_bytes(&security.aes_key)
     );
+    let session_key = crypto::derive_session_key(&security.aes_key);
+    println!(
+        "AES Key (decrypted):  {}",
+        format_hex_bytes(&session_key)
+    );
 
     if security.export_table == 0 {
         println!("Export Table:         0x00000000 (none)");