ZIYE-JK/dsh-quadrant-todo

Four-quadrant todo manager in the DSH sidebar with month and week calendar views, per-period completion statistics, system notifications and Feishu notifications (the latter needs the DSH Feishu integration), and recurrence rules including Chinese statutory workdays and the Ebbinghaus curve. Derived from Natte/dsh-sidebar-todo 0.2.3 and largely rewritten; do not install both — they register the same /todo/api route and use the same todos.json data file.