fix: resolve compilation errors by fixing mutable references and removing unused imports

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/modes/common.rs

@@ -133,7 +133,7 @@ pub fn store_item_digest_value(
     // Save digest to meta
     let digest_meta_name = get_digest_type_meta(digest_type);
     let digest_meta = Meta {
-        id: item.id.unwrap(),
+        id: item.id.ok_or_else(|| anyhow!("Item missing ID"))?,
         name: digest_meta_name,
         value: digest_value,
     };

src/modes/diff.rs

@@ -1,6 +1,5 @@
 use anyhow::{anyhow, Result};
 use clap::Command;
-use log::debug;
 use std::io::Read;
 use std::os::fd::FromRawFd;
 use std::str::FromStr;

src/modes/save.rs

@@ -240,7 +240,7 @@ pub fn mode_save(
     setup_item_metadata(conn, args, &item, tags)?; // Pass mutable reference
 
     // Use a transaction for database operations to ensure atomicity
-    let tx = conn.transaction()?;
+    let mut tx = conn.transaction()?;
 
     let item_meta = collect_item_meta(args);
     let item_id = item.id.ok_or_else(|| anyhow!("Item missing ID"))?;

src/modes/update.rs

@@ -101,7 +101,7 @@ pub fn mode_update(
 
             // Save digest to meta using the common function
             // Pass the transaction directly instead of calling into_inner()
-            store_item_digest_value(&tx, item.clone(), digest_type, digest_value)?;
+            store_item_digest_value(&mut tx, item.clone(), digest_type, digest_value)?;
         } else {
             debug!(
                 "MAIN: Unable to update digest of item due to missing file {:?}",