Fix update_task: always set updated_at to now()

Local edits must always update updated_at to the current time.
The task.updated_at field is only relevant for insert_task
(API-synced tasks have a real server timestamp).

src/infrastructure/db.rs

@@ -183,9 +183,6 @@ impl Db {
             TaskStatus::Completed => "completed",
             TaskStatus::NeedsAction => "needsAction",
         };
-        let updated_at = task
-            .updated_at
-            .unwrap_or_else(|| chrono::Utc::now().naive_utc());
         let conn = self.conn.lock().unwrap();
         conn.execute(
             "UPDATE tasks SET title=?1, notes=?2, status=?3, due=?4, position=?5, updated_at=?6
@@ -196,7 +193,7 @@ impl Db {
                 status_str,
                 due_str,
                 task.position,
-                updated_at.format("%Y-%m-%d %H:%M:%S").to_string(),
+                chrono::Utc::now().format("%Y-%m-%d %H:%M:%S").to_string(),
                 task.id,
             ],
         )?;