Calendar panel: a picked mini-calendar day showed nowhere; no new-tab link on a phone

In Mail's side panel the agenda already lists the whole month and the mini
calendar never marked a selection, so clicking a day in the current month
changed nothing on screen. The day is now highlighted and the agenda scrolls to
it (TODAY scrolls back); a day in another month flips both to that month.

On a phone the panel drops the "Open calendar in new tab" footer: the host
passes newTabLink: false to the embedded calendar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/components/mail/RightPanel.tsx

@@ -12,6 +12,7 @@ import { useT } from "../../i18n";
 import { api, apiFetch } from "../../lib/api";
 import type { Address, AttachmentOut, MessageEnvelope, ThreadDetail } from "../../lib/types";
 import { AvatarImage } from "../SenderAvatar";
+import { useIsMobile } from "../../lib/useIsMobile";
 import { loadBundle } from "../../plugins/bundleLoader";
 import { usePluginContext } from "../../plugins/context";
 import { isPreviewable } from "../thread/previewKind";
@@ -123,6 +124,8 @@ const CAL_BUNDLE = "/api/plugins/calendar/ui/page.js";
 function PanelCalendar({ invite }: { invite: InviteSignal | null }) {
   const ref = useRef<HTMLDivElement>(null);
   const ctx = usePluginContext("calendar");
+  // A phone has no use for "Open calendar in new tab".
+  const mobile = useIsMobile();
   // Remount when a new "Invite all" fires so the form opens with those guests.
   const inviteN = invite?.n ?? 0;
   useEffect(() => {
@@ -131,11 +134,15 @@ function PanelCalendar({ invite }: { invite: InviteSignal | null }) {
     loadBundle(CAL_BUNDLE).then((mount) => {
       if (!alive || !ref.current) return;
       ref.current.innerHTML = "";
-      cleanup = mount(ref.current, ctx, { embed: "panel", newEventGuests: invite?.guests });
+      cleanup = mount(ref.current, ctx, {
+        embed: "panel",
+        newEventGuests: invite?.guests,
+        newTabLink: !mobile,
+      });
     });
     return () => { alive = false; if (typeof cleanup === "function") cleanup(); };
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [ctx, inviteN]);
+  }, [ctx, inviteN, mobile]);
   return <div ref={ref} className="h-full" />;
 }