fix: update md5 usage and remove unused imports

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/services/item_service.rs

@@ -346,7 +346,7 @@ impl ItemService {
             MetaPluginType::Binary,
             MetaPluginType::LineCount,
             MetaPluginType::WordCount,
-            MetaPluginType::DigestSha256,
+            MetaPluginType::Digest,
             MetaPluginType::User,
             MetaPluginType::Hostname,
         ];

src/services/meta_service.rs

@@ -1,6 +1,6 @@
 use crate::config::Settings;
 use crate::meta_plugin::{get_meta_plugin, MetaPlugin, MetaPluginType};
-use crate::modes::common::{settings_digest_type, settings_meta_plugin_types};
+use crate::modes::common::settings_meta_plugin_types;
 use clap::Command;
 use log::debug;
 use rusqlite::Connection;