fix: resolve mutable borrowing issues with Transaction and clean up warnings

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

src/modes/save.rs

@@ -202,7 +202,7 @@ fn process_input_stream(
 }
 
 fn finalize_meta_plugins(
-    conn: &mut rusqlite::Connection, // Changed to mutable reference
+    conn: &rusqlite::Connection,
     meta_plugins: &mut Vec<Box<dyn crate::meta_plugin::MetaPlugin>>,
     item: &crate::db::Item,
 ) -> Result<(), anyhow::Error> {
@@ -264,8 +264,8 @@ pub fn mode_save(
     item.size = processed_item.size;
     item.compression = compression_type.to_string();
 
-    // Pass the transaction as mutable reference directly
-    finalize_meta_plugins(&mut tx, &mut meta_plugins, &item)?;
+    // Pass the transaction directly (not as mutable reference)
+    finalize_meta_plugins(&tx, &mut meta_plugins, &item)?;
     crate::db::update_item(&tx, item.clone())?;
     
     // Commit the transaction

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(&mut tx, item.clone(), digest_type, digest_value)?;
+            store_item_digest_value(&tx, item.clone(), digest_type, digest_value)?;
         } else {
             debug!(
                 "MAIN: Unable to update digest of item due to missing file {:?}",