feat: P2.2 Create Appointment from Email + P2.4 Calendar Dashlet + P2.12 Action Wheel + P2.14 Share Files

- P2.2: 'Create Appointment' button in email viewer → pre-fills event modal
  with subject, body, participants, date. calendar-store newEventPrefill state.
- P2.4: MiniCalendarDashlet in sidebar bottom — month grid with event dots,
  day click navigates to calendar. Collapsible, respect firstDayOfWeek.
- P2.12: Custom radial menu (components/ui/radial-menu.tsx) — circular SVG
  menu with keyboard nav, animations. Wired into email-list, contact-list,
  file-browser, calendar-month-view right-click handlers.
- P2.14: 'Send as Attachment' button in file browser — opens compose tab
  with selected files pre-attached via Pro tab store.

components/layout/sidebar.tsx

@@ -4,6 +4,7 @@ import { useState, useEffect, useMemo, ReactNode } from "react";
 import { useTranslations } from "next-intl";
 import { useRouter } from "@/i18n/navigation";
 import { PluginSlot } from "@/components/plugins/plugin-slot";
+import { MiniCalendarDashlet } from "@/components/calendar/mini-calendar-dashlet";
 import { Button } from "@/components/ui/button";
 import {
   Inbox,
@@ -62,6 +63,7 @@ import { useUIStore } from "@/stores/ui-store";
 import { useAuthStore } from "@/stores/auth-store";
 import { useVacationStore } from "@/stores/vacation-store";
 import { useSettingsStore, getKeywordVisibility } from "@/stores/settings-store";
+import { usePolicyStore } from "@/stores/policy-store";
 import { useEmailStore } from "@/stores/email-store";
 import { toast } from "@/stores/toast-store";
 import { debug } from "@/lib/debug";
@@ -808,6 +810,12 @@ export function Sidebar({
       return stored !== null ? JSON.parse(stored) : true;
     } catch { return true; }
   });
+  const [calendarDashletExpanded, setCalendarDashletExpanded] = useState(() => {
+    try {
+      const stored = localStorage.getItem('sidebarCalendarDashletExpanded');
+      return stored !== null ? JSON.parse(stored) : true;
+    } catch { return true; }
+  });
   const [unifiedExpanded, setUnifiedExpanded] = useState(() => {
     try {
       const stored = localStorage.getItem('sidebarUnifiedExpanded');
@@ -840,6 +848,7 @@ export function Sidebar({
   const emailKeywords = useSettingsStore(s => s.emailKeywords);
   const nestedTags = useSettingsStore(s => s.nestedTags);
   const isEmbedded = useIsEmbedded();
+  const calendarEnabled = usePolicyStore((s) => s.isFeatureEnabled('calendarEnabled'));
   // The Pro shell owns the global chrome (rail + tab bar), so the sidebar's
   // own AccountSwitcher would be a redundant second account UI in the same
   // pane.
@@ -1054,6 +1063,13 @@ export function Sidebar({
       return next;
     });
   };
+  const toggleCalendarDashlet = () => {
+    setCalendarDashletExpanded((prev: boolean) => {
+      const next = !prev;
+      try { localStorage.setItem('sidebarCalendarDashletExpanded', JSON.stringify(next)); } catch { /* */ }
+      return next;
+    });
+  };
   const toggleShared = () => {
     setSharedExpanded((prev: boolean) => {
       const next = !prev;
@@ -1405,6 +1421,18 @@ export function Sidebar({
           </div>
         )}
 
+        {!isCollapsed && calendarEnabled && (
+          <div>
+            <SidebarSectionHeader
+              label={t("calendar")}
+              expanded={calendarDashletExpanded}
+              onToggle={toggleCalendarDashlet}
+              isCollapsed={isCollapsed}
+            />
+            {calendarDashletExpanded && <MiniCalendarDashlet />}
+          </div>
+        )}
+
         {!isCollapsed && <PluginSlot name="sidebar-widget" className="border-t border-border" />}
       </div>