refactor: move meta plugin finalization logic into meta plugins

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

src/meta_plugin/digest.rs

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