Wire ShareButton into list/note/calendar pages; fix nav and calendar select labels

- Add ShareButton to list detail, note editor, and calendar event panel
- Add Settings gear icon to AppNav (core page not in module registry)
- Fix calendar event dialog showing raw UUID: pass explicit children to
  SelectValue so labels display before SelectContent mounts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/calendar/components/calendar-shell.tsx

@@ -11,6 +11,7 @@ import { useMemo, useState, useTransition } from "react";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
+import { ShareButton } from "@/components/share-button";
 import {
   Select,
   SelectContent,
@@ -307,7 +308,9 @@ export function CalendarShell({
                   }
                 >
                   <SelectTrigger aria-label={`${calendar.name} visibility`}>
-                    <SelectValue />
+                    <SelectValue>
+                      {calendar.visibility === "household" ? "Household" : "Private"}
+                    </SelectValue>
                   </SelectTrigger>
                   <SelectContent>
                     <SelectItem value="household">Household</SelectItem>
@@ -353,7 +356,9 @@ export function CalendarShell({
                 }
               >
                 <SelectTrigger aria-label="Calendar visibility">
-                  <SelectValue />
+                  <SelectValue>
+                    {calendarVisibility === "household" ? "Household" : "Private"}
+                  </SelectValue>
                 </SelectTrigger>
                 <SelectContent>
                   <SelectItem value="household">Household</SelectItem>
@@ -431,7 +436,9 @@ export function CalendarShell({
                 }
               >
                 <SelectTrigger id="event-calendar">
-                  <SelectValue />
+                  <SelectValue>
+                    {calendarRows.find((c) => c.id === selectedEvent.calendarId)?.name ?? "Select a calendar"}
+                  </SelectValue>
                 </SelectTrigger>
                 <SelectContent>
                   {calendarRows.map((calendar) => (
@@ -483,16 +490,21 @@ export function CalendarShell({
                 }
               />
               <div className="flex items-center justify-between gap-2 pt-2">
-                <div>
+                <div className="flex gap-2">
                   {selectedEvent.id && (
                     <Button variant="destructive" onClick={removeSelectedEvent}>
                       Delete event
                     </Button>
                   )}
                 </div>
-                <Button onClick={saveSelectedEvent} disabled={!selectedEvent.title || isPending}>
-                  Save event
-                </Button>
+                <div className="flex gap-2">
+                  {selectedEvent.id && (
+                    <ShareButton entityType="calendar.event" entityId={selectedEvent.id} />
+                  )}
+                  <Button onClick={saveSelectedEvent} disabled={!selectedEvent.title || isPending}>
+                    Save event
+                  </Button>
+                </div>
               </div>
             </div>
           </div>