feat: parse and display security info (M3)

Implement security info parsing including RSA signature, encrypted AES
key, image/region/media flags, load address, SHA-1 digests, and page
descriptors with section type classification. Add comprehensive unit
and integration tests.

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

src/lib.rs

@@ -10,11 +10,13 @@ pub mod display;
 pub mod error;
 pub mod header;
 pub mod optional;
+pub mod security;
 pub mod util;
 
 use error::Result;
 use header::Xex2Header;
 use optional::OptionalHeaders;
+use security::SecurityInfo;
 
 /// A parsed XEX2 file containing all extracted structures.
 #[derive(Debug)]
@@ -23,6 +25,8 @@ pub struct Xex2File {
     pub header: Xex2Header,
     /// All parsed optional headers.
     pub optional_headers: OptionalHeaders,
+    /// Security info (signatures, keys, page descriptors).
+    pub security_info: SecurityInfo,
 }
 
 /// Parses an XEX2 file from a byte slice.
@@ -32,9 +36,11 @@ pub struct Xex2File {
 pub fn parse(data: &[u8]) -> Result<Xex2File> {
     let header = header::parse_header(data)?;
     let optional_headers = optional::parse_optional_headers(data, &header)?;
+    let security_info = security::parse_security_info(data, header.security_offset)?;
 
     Ok(Xex2File {
         header,
         optional_headers,
+        security_info,
     })
 }