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/notes/components/note-editor.tsx

@@ -6,6 +6,7 @@ import { 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 type { NoteDto } from "../server/queries";
 import { createNote, deleteNote, setNotePinned, updateNote } from "../server/actions";
 import { MarkdownPreview } from "./markdown-preview";
@@ -76,6 +77,9 @@ export function NoteEditor({ note }: { note?: NoteDto }) {
               {pinned ? "Unpin note" : "Pin note"}
             </Button>
           ) : null}
+          {currentNote ? (
+            <ShareButton entityType="notes.note" entityId={currentNote.id} />
+          ) : null}
           {currentNote ? (
             <Button variant="destructive" onClick={removeNote} disabled={isPending}>
               <Trash2 />