Fix code quality: trailing whitespace, unused imports, clippy warnings

- Fix trailing whitespace in kex.rs and s3.rs
- Add missing KexProposal import in kex_complete.rs
- Auto-fix clippy warnings across all crates
- All 153 tests pass

markbase-core/src/download/handlers.rs

@@ -1,27 +1,22 @@
 use axum::{
-    extract::{Path, State},
-    http::{HeaderMap, StatusCode},
-    response::{Html, IntoResponse, Json},
+    extract::Path,
+    http::StatusCode,
+    response::{IntoResponse, Json},
 };
 use serde_json::json;
 use std::path::PathBuf;
 
-use crate::server::AppState;
 use crate::download::storage;
 
-pub async fn list_uploaded_files(
-    Path(user_id): Path<String>,
-) -> impl IntoResponse {
+pub async fn list_uploaded_files(Path(user_id): Path<String>) -> impl IntoResponse {
     let file_list = storage::scan_uploaded_files(&user_id);
     (StatusCode::OK, Json(file_list))
 }
 
-pub async fn get_file_info(
-    Path((user_id, filename)): Path<(String, String)>,
-) -> impl IntoResponse {
+pub async fn get_file_info(Path((user_id, filename)): Path<(String, String)>) -> impl IntoResponse {
     let base_path = format!("/Users/accusys/Downloads/{}", user_id);
     let file_path = PathBuf::from(&base_path).join(&filename);
-    
+
     if !file_path.exists() {
         return (
             StatusCode::NOT_FOUND,
@@ -29,7 +24,7 @@ pub async fn get_file_info(
         )
             .into_response();
     }
-    
+
     let metadata = std::fs::metadata(&file_path).unwrap();
     let file_size = metadata.len();
     let file_hash = if file_size > 0 {
@@ -37,7 +32,7 @@ pub async fn get_file_info(
     } else {
         Some("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855".to_string())
     };
-    
+
     (
         StatusCode::OK,
         Json(json!({
@@ -49,4 +44,4 @@ pub async fn get_file_info(
         })),
     )
         .into_response()
-}
+}