fix: Fix unused imports and ProgramWriter issues

src/digest_engine/none.rs

@@ -1,6 +1,6 @@
 use anyhow::Result;
 use crate::digest_engine::DigestEngine;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::io;
 
 #[derive(Debug, Eq, PartialEq, Clone, Default)]

src/digest_engine/program.rs

@@ -1,10 +1,10 @@
-use anyhow::{anyhow, Context, Result};
+use anyhow::{anyhow, Result};
 use log::*;
 use std::env;
 use std::fs;
 use std::fs::File;
 use std::io;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::os::unix::fs::PermissionsExt;
 use std::path::PathBuf;
 use std::process::{Command, Stdio};
@@ -70,7 +70,7 @@ impl DigestEngine for DigestEngineProgram {
         Ok("program".to_string())
     }
     
-    fn update(&mut self, data: &[u8]) {
+    fn update(&mut self, _data: &[u8]) {
         // This is handled by the ProgramWriter implementation
     }
 }

src/digest_engine/sha2.rs

@@ -1,8 +1,6 @@
 use anyhow::Result;
 use log::*;
-use std::fs::File;
-use std::io::{Read, Write};
-use std::path::PathBuf;
+use std::io::Write;
 use sha2::{Digest, Sha256};
 use std::io;