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/s3_auth.rs

@@ -8,11 +8,11 @@ type HmacSha256 = Hmac<Sha256>;
 pub fn verify_signature(headers: HeaderMap, method: &str, path: &str) -> bool {
     // Load S3 config and check require_auth flag
     let config = crate::s3_config::S3Config::load_default().unwrap_or_default();
-    
+
     // Merge environment variables (allows override via MB_S3_REQUIRE_AUTH)
     let mut config = config;
     config.merge_env();
-    
+
     if !config.s3.require_auth {
         // Development mode: allow access without authentication
         return true;
@@ -127,7 +127,7 @@ fn calculate_signature(
     headers: HeaderMap,
     method: &str,
     path: &str,
-    access_key: &str,
+    _access_key: &str,
     secret_key: &str,
     region: &str,
     service: &str,
@@ -143,9 +143,9 @@ fn calculate_signature(
     let signing_key = calculate_signing_key(secret_key, date, region, service);
 
     // 4. Calculate Signature
-    let signature = hmac_sha256_hex(&signing_key, &string_to_sign);
+    
 
-    signature
+    hmac_sha256_hex(&signing_key, &string_to_sign)
 }
 
 fn create_canonical_request(headers: HeaderMap, method: &str, path: &str) -> String {