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/tools/mod.rs

@@ -17,4 +17,4 @@ pub async fn handle_tools_command(cmd: ToolsCommands) -> anyhow::Result<()> {
         ToolsCommands::Test(c) => test::handle_test_command(c)?,
     }
     Ok(())
-}
+}

markbase-core/src/cli/tools/render.rs

@@ -23,4 +23,4 @@ pub fn handle_render_command(cmd: RenderCommand) -> anyhow::Result<()> {
         }
     }
     Ok(())
-}
+}

markbase-core/src/cli/tools/test.rs

@@ -16,36 +16,39 @@ pub enum TestCommand {
 
 pub fn handle_test_command(cmd: TestCommand) -> anyhow::Result<()> {
     match cmd {
-        TestCommand::Bcrypt { password, verify_hash } => {
+        TestCommand::Bcrypt {
+            password,
+            verify_hash,
+        } => {
             use bcrypt::{hash, verify, DEFAULT_COST};
 
             println!("=== bcrypt Hash Test ===");
             println!("Password: {}", password);
-            println!("");
+            println!();
 
             let new_hash = hash(&password, DEFAULT_COST)?;
             println!("Generated hash:");
             println!("{}", new_hash);
-            println!("");
+            println!();
 
             if let Some(hash_to_verify) = verify_hash {
                 println!("Verifying hash: {}", hash_to_verify);
                 let valid = verify(&password, &hash_to_verify)?;
                 println!("Valid: {}", valid);
-                println!("");
+                println!();
             }
 
             let db_hash = "$2b$10$ha5wU.mOi8fHLJCfun860u2cfVopa04jwe/q82IKOwqp5uG70qsH6";
             println!("Database hash: {}", db_hash);
             let valid = verify(&password, db_hash)?;
             println!("Database hash valid for '{}': {}", password, valid);
-            println!("");
+            println!();
 
             if !valid {
                 println!("❌ Database hash is incorrect!");
                 println!("Update SQL:");
                 println!("UPDATE sftpgo_users SET password_hash = '{}' WHERE username IN ('testuser', 'demo', 'warren', 'momentry');", new_hash);
-                println!("");
+                println!();
                 println!("Execute:");
                 println!("sqlite3 data/auth.sqlite \"UPDATE sftpgo_users SET password_hash = '{}' WHERE username IN ('testuser', 'demo', 'warren', 'momentry');\"", new_hash);
             } else {
@@ -58,4 +61,4 @@ pub fn handle_test_command(cmd: TestCommand) -> anyhow::Result<()> {
         }
     }
     Ok(())
-}
+}