fix: change self reference to mutable in save_meta and remove unused imports

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

src/meta_plugin.rs

@@ -64,7 +64,7 @@ pub trait MetaPlugin {
     }
     
     // Save metadata to database
-    fn save_meta(&self, conn: &Connection, item_id: i64, value: String) -> Result<()> {
+    fn save_meta(&mut self, conn: &Connection, item_id: i64, value: String) -> Result<()> {
         let meta = crate::db::Meta {
             id: item_id,
             name: self.meta_name(),

src/meta_plugin/digest.rs

@@ -3,7 +3,6 @@ use sha2::{Digest, Sha256};
 use std::io;
 use std::io::Write;
 use std::time::Instant;
-use rusqlite::Connection;
 
 use crate::meta_plugin::MetaPlugin;
 

src/meta_plugin/program.rs

@@ -5,7 +5,6 @@ use std::io;
 use std::io::Write;
 use std::process::{Command, Stdio};
 use which::which;
-use rusqlite::Connection;
 
 use crate::meta_plugin::MetaPlugin;