fix: perbaiki 5 warning clippy pre-existing (base untuk TUI overhaul)

unnested_or_patterns, collapsible_if, items_after_statements, dan
case_sensitive_file_extension_comparisons di auto.rs, engine.rs, dan
actions/mod.rs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/subagent/engine.rs

@@ -8,6 +8,7 @@
 //! are not a weaker link than the main agent.
 
 use std::fmt::Write;
+use sha2::Digest;
 use tokio::sync::mpsc;
 use crate::dto::chat::message::ChatMessage;
 use crate::dto::provider::request::ToolDef;
@@ -456,7 +457,6 @@ pub fn run_subagent(ctx: &SubagentContext, tx: &mpsc::Sender<SubagentEvent>) ->
                                         .unwrap_or("unknown");
                                     let content_sha256 = {
                                         let content = args.get("content").or_else(|| args.get("new"));
-                                        use sha2::Digest;
                                         let hash = sha2::Sha256::digest(
                                             content.and_then(|v| v.as_str()).unwrap_or("").as_bytes(),
                                         );