style(server): fix all clippy warnings including derivable traits, redundant locals, collapsible blocks and needless borrows

server/src/handlers_v2/tasks.rs

@@ -216,11 +216,10 @@ impl McpTool for UpdateTaskStatusHandler {
                     }
 
                     for (idx, t) in tasks.iter().enumerate() {
-                        if let Some(pid) = &t.parent_id {
-                            if let Some(&p_idx) = id_to_idx.get(pid.as_str()) {
+                        if let Some(pid) = &t.parent_id
+                            && let Some(&p_idx) = id_to_idx.get(pid.as_str()) {
                                 children_map.entry(p_idx).or_default().push(idx);
                             }
-                        }
                     }
 
                     if let Some(&start_idx) = id_to_idx.get(target_id.as_str()) {