feat: Expandable ping chart on the public Status Page

📑 I have found these related issues/pull requests I searched for existing Status Page and ping/latency-related discussions. Several threads touch heartbeat history or Status Page presentation, but none deliver an optional, collapsed-by-default expandable panel with response-time metrics and a ping chart on the public Status Page. This request is scoped specifically to that UX and a settings toggle, not a general dashboard redesign. 🔖 Feature description The public Status Page currently shows each monitor as a compact row (name, uptime badge, heartbeat bar). That answers “up or down,” but not “is it slow?” Latency and short-term response-time history are available in the admin dashboard, not on the public page. We want the public Status Page to optionally expose response-time context per monitor in an expandable row, so visitors can inspect latency without opening the admin UI. ✔️ Solution Add an optional Status Page setting: “Show ping chart” (default OFF). When enabled: •…