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

filetree-sled/src/lib.rs

@@ -286,9 +286,9 @@ impl FileTreeSled {
         label: &str,
         file_uuid: &str,
         sha256: Option<&str>,
-        original_name: &str,
+        _original_name: &str,
         file_size: Option<i64>,
-        mime_type: Option<&str>,
+        _mime_type: Option<&str>,
         parent_id: Option<&str>,
     ) -> FileNode {
         FileNode {
@@ -314,7 +314,7 @@ impl FileTreeSled {
 
 pub fn build_tree(nodes: &[FileNode]) -> Vec<FileNode> {
     let mut roots = Vec::new();
-    let node_map: HashMap<String, &FileNode> =
+    let _node_map: HashMap<String, &FileNode> =
         nodes.iter().map(|n| (n.node_id.clone(), n)).collect();
 
     for node in nodes {