feat(02-02): implement pack, unpack, and inspect archive commands

- pack: two-pass algorithm reads/hashes/compresses/encrypts files then writes header+TOC+data
- inspect: reads header and TOC, displays all metadata (sizes, offsets, IVs, HMACs, SHA-256)
- unpack: HMAC-first verification, AES-256-CBC decryption, optional gzip decompression, SHA-256 check
- CLI dispatch wired from main.rs to archive module
- Directory traversal protection: rejects filenames starting with / or containing ..
- Compression auto-detection: .apk/.zip/etc stored without gzip (flags=0x00 when no file compressed)
- Round-trip verified: pack+unpack produces byte-identical files
- HMAC tamper detection verified: flipped ciphertext byte triggers rejection

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

src/main.rs

@@ -17,27 +17,18 @@ fn main() -> anyhow::Result<()> {
             output,
             no_compress,
         } => {
-            println!(
-                "Pack: {} files -> {:?} (no_compress: {:?})",
-                files.len(),
-                output,
-                no_compress
-            );
-            println!("Not implemented yet");
-            Ok(())
+            archive::pack(&files, &output, &no_compress)?;
         }
         Commands::Unpack {
             archive,
             output_dir,
         } => {
-            println!("Unpack: {:?} -> {:?}", archive, output_dir);
-            println!("Not implemented yet");
-            Ok(())
+            archive::unpack(&archive, &output_dir)?;
         }
         Commands::Inspect { archive } => {
-            println!("Inspect: {:?}", archive);
-            println!("Not implemented yet");
-            Ok(())
+            archive::inspect(&archive)?;
         }
     }
+
+    Ok(())
 }