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/cli/storage/sync.rs

@@ -17,27 +17,31 @@ pub enum SyncCommand {
 
 pub fn handle_sync_command(cmd: SyncCommand) -> anyhow::Result<()> {
     match cmd {
-        SyncCommand::Start { source, target, mode } => {
+        SyncCommand::Start {
+            source,
+            target,
+            mode,
+        } => {
             use std::path::Path;
-            
+
             println!("Syncing {} to {} (mode: {})", source, target, mode);
-            
+
             let source_path = Path::new(&source);
             let target_path = Path::new(&target);
-            
+
             if !source_path.exists() {
                 return Err(anyhow::anyhow!("Source path not found: {}", source));
             }
-            
+
             if mode == "mirror" {
                 std::fs::create_dir_all(target_path)?;
-                
+
                 let entries = std::fs::read_dir(source_path)?;
                 for entry in entries {
                     let entry = entry?;
                     let path = entry.path();
                     let target_file = target_path.join(entry.file_name());
-                    
+
                     if path.is_file() {
                         std::fs::copy(&path, &target_file)?;
                         println!("  Copied: {:?}", entry.file_name());
@@ -46,7 +50,7 @@ pub fn handle_sync_command(cmd: SyncCommand) -> anyhow::Result<()> {
                         println!("  Created directory: {:?}", entry.file_name());
                     }
                 }
-                
+
                 println!("✓ Sync completed (mirror mode)");
             } else {
                 return Err(anyhow::anyhow!("Unknown sync mode: {}. Use 'mirror'", mode));
@@ -59,4 +63,4 @@ pub fn handle_sync_command(cmd: SyncCommand) -> anyhow::Result<()> {
         }
     }
     Ok(())
-}
+}