fix(mysql): initialize transaction query timing

crates/dbx-drivers/src/db/mysql.rs

@@ -5350,6 +5350,7 @@ pub async fn execute_transaction_statement_on_conn(
             rows: Vec::new(),
             affected_rows,
             execution_time_ms: started_at.elapsed().as_millis(),
+            server_execute_time_us: None,
             truncated: false,
             session_id: None,
             has_more: false,
@@ -5383,6 +5384,7 @@ pub async fn execute_transaction_statement_on_conn(
             rows,
             affected_rows: 0,
             execution_time_ms: started_at.elapsed().as_millis(),
+            server_execute_time_us: None,
             truncated,
             session_id: None,
             has_more: false,

crates/dbx-mcp/src/http.rs

@@ -194,6 +194,7 @@ mod tests {
                     rows: Vec::new(),
                     affected_rows: 0,
                     execution_time_ms: 0,
+                    server_execute_time_us: None,
                     truncated: false,
                     session_id: None,
                     has_more: false,

crates/dbx-mcp/src/server.rs

@@ -2629,6 +2629,7 @@ fn empty_query_result() -> dbx_core::db::QueryResult {
         rows: Vec::new(),
         affected_rows: 0,
         execution_time_ms: 0,
+        server_execute_time_us: None,
         truncated: false,
         session_id: None,
         has_more: false,
@@ -3419,6 +3420,7 @@ mod tests {
                     rows: Vec::new(),
                     affected_rows: 0,
                     execution_time_ms: 0,
+                    server_execute_time_us: None,
                     truncated: false,
                     session_id: None,
                     has_more: false,

crates/dbx-mcp/src/transaction.rs

@@ -799,6 +799,7 @@ mod tests {
             rows: Vec::new(),
             affected_rows: 0,
             execution_time_ms: 0,
+            server_execute_time_us: None,
             truncated: false,
             session_id: None,
             has_more: false,