feat: voice messages, offline queue, delivery ticks, volume slider, admin + scaling

- Voice messages: MediaRecorder → encrypted attachment, custom waveform
  player via OfflineAudioContext, 60s limit + live mic-level meter
- Offline message queue: localStorage outbox, exponential backoff retries,
  optimistic pending bubble with retry/discard
- Delivery indicator: message_deliveries table + RLS (reciprocal receipts),
  ✓ / ✓✓ / ✓✓-blue tick states, group-aware (all members must ack)
- Per-participant volume slider in calls via right-click tile menu,
  persisted to localStorage, applied to attached audio elements
- Group call scaling: grid up to 12 tiles with pagination,
  active-speaker auto-promotion in fullscreen
- Push notifications scaffolding: service worker, VAPID subscription
  registration, notify-push edge function skeleton
- Backup recovery code: 24-char base32 code (~120 bits entropy) as
  alternative decrypt path, restore UI with mode toggle
- Admin panel: conversations list, audit log (admin_audit_log table +
  admin_log_action RPC), audit entry on user flag toggle
- Search v2: sender filter, attachment-only toggle, date range
- Reactions pop animation (scale 0.4→1.15→1 on count change)
- Message list windowing (150 default, expand via IntersectionObserver)
- Stub cleanup: removed dead ScreenshareStub from CallParticipantTile

Fixes:
- Focus-triggered flicker: dropped window.focus listeners in three spots,
  throttled visibilitychange/online wake-refreshes to 30s, keep existing
  data visible during background re-syncs (no more spinner on every click)
- Voice attachment audio element collapsed to 0px on peer side — now
  forces 280px min-width on bubble

Migrations (push required):
  20260421000001_message_deliveries.sql
  20260421000002_admin_audit_log.sql

Server TODO:
  VAPID keys + notify-push edge function deploy

apps/desktop/src/components/MessageBubble.tsx

@@ -13,6 +13,7 @@ import { useAuth } from '../context/AuthContext';
 import { devLocalSecretStore } from '../lib/secretStore';
 import { supabase } from '../lib/supabase';
 import type { AggregatedReaction } from '../lib/useMessageReactions';
+import { AttachmentAudio } from './AttachmentAudio';
 import { AttachmentImage } from './AttachmentImage';
 import { Avatar } from './Avatar';
 import { ForwardIcon, PencilIcon, PhoneIcon, PhoneOffIcon, ReplyIcon, SmileIcon, SpinnerIcon, TrashIcon, XIcon } from './icons';
@@ -40,6 +41,8 @@ interface Props {
   reactions: AggregatedReaction[];
   onToggleReaction: (emoji: string) => Promise<void>;
   showSeen?: boolean;
+  /** Delivery state for own messages: 'sent' / 'delivered' / 'read'. */
+  deliveryState?: 'sent' | 'delivered' | 'read';
   /** Resolved quoted message info (parent does the lookup). */
   quoted?: QuotedRef | null;
   /** Tap-to-jump on quote bubble. Receives the quoted message's id. */
@@ -63,6 +66,7 @@ export function MessageBubble({
   reactions,
   onToggleReaction,
   showSeen = false,
+  deliveryState,
   quoted = null,
   onJumpToMessage,
   onReply,
@@ -296,9 +300,13 @@ export function MessageBubble({
             ) : (
               <>
                 {bodyText.length > 0 && <div>{bodyText}</div>}
-                {attachments.map((a) => (
-                  <AttachmentImage key={a.id} handle={a} />
-                ))}
+                {attachments.map((a) =>
+                  a.mimeType.startsWith('audio/') ? (
+                    <AttachmentAudio key={a.id} handle={a} />
+                  ) : (
+                    <AttachmentImage key={a.id} handle={a} />
+                  ),
+                )}
               </>
             )}
             <div
@@ -315,21 +323,24 @@ export function MessageBubble({
           </div>
         )}
 
-        {showSeen && mine && !editing && !message.deletedAt && (
-          <p className="mt-0.5 text-right text-[10px] text-fg-muted">
-            {t('app:chats.seen')}
-          </p>
+        {mine && !editing && !message.deletedAt && deliveryState && (
+          <div className="mt-0.5 flex items-center justify-end gap-1 text-[10px] text-fg-muted">
+            <DeliveryTicks state={deliveryState} />
+            {showSeen && <span>{t('app:chats.seen')}</span>}
+          </div>
         )}
 
         {reactions.length > 0 && !editing && (
           <div className={'mt-1 flex flex-wrap gap-1 ' + (mine ? 'justify-end' : 'justify-start')}>
             {reactions.map((r) => (
               <button
-                key={r.emoji}
+                // Keying by emoji+count makes React remount the chip when the
+                // count flips, replaying the pop animation. Cheap visual cue.
+                key={r.emoji + ':' + r.count}
                 type="button"
                 onClick={() => void onToggleReaction(r.emoji)}
                 className={
-                  'inline-flex cursor-pointer items-center gap-1 rounded-full border px-2 py-0.5 text-xs transition focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/40 ' +
+                  'inline-flex origin-bottom animate-reaction-pop cursor-pointer items-center gap-1 rounded-full border px-2 py-0.5 text-xs transition focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/40 ' +
                   (r.mine
                     ? 'border-accent/40 bg-accent/20 text-accent'
                     : 'border-line bg-surface-2 text-fg hover:bg-surface-3')
@@ -499,6 +510,45 @@ function formatDuration(totalSec: number): string {
   return m + ':' + s.toString().padStart(2, '0');
 }
 
+function DeliveryTicks({ state }: { state: 'sent' | 'delivered' | 'read' }) {
+  // One checkmark for sent, two for delivered/read. Read shifts color to the
+  // accent to match WhatsApp/Telegram blue-tick convention.
+  const color =
+    state === 'read'
+      ? 'text-sky-500 dark:text-sky-400'
+      : 'text-fg-muted';
+  return (
+    <span
+      aria-label={
+        state === 'read'
+          ? 'Gelesen'
+          : state === 'delivered'
+            ? 'Zugestellt'
+            : 'Gesendet'
+      }
+      title={
+        state === 'read'
+          ? 'Gelesen'
+          : state === 'delivered'
+            ? 'Zugestellt'
+            : 'Gesendet'
+      }
+      className={'flex items-center ' + color}
+    >
+      <svg viewBox="0 0 16 12" width="14" height="10" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+        {state === 'sent' ? (
+          <polyline points="2 7 6 11 14 1" />
+        ) : (
+          <>
+            <polyline points="1 7 5 11 11 2" />
+            <polyline points="6 11 10 11 14 1" />
+          </>
+        )}
+      </svg>
+    </span>
+  );
+}
+
 function ActionButton({
   label,
   onClick,