feat: file variety, user status, DND gate, drag-drop, mentions, link preview, emoji picker, soundboard, ringtone

Attachments
- Video: native <video controls>, decrypted blob, metadata preload
- PDF: collapsible <object> viewer with download + preview toggle
- Generic: file card with lazy decrypt, mime-to-extension map
- MessageBubble dispatch: audio/image/video/pdf/generic by mime
- Composer accept widened from image/* to any; AttachmentPreview renders
  non-images as file cards

User status
- usePeerPresence returns { state, statusMessage } and tracks both fields
  via realtime updates
- ConversationHeader subtitle shows custom status_message when peer is
  online/idle/dnd (with message set); falls back to localized presence
  label; always "Offline" when state === 'offline'
- UserBar: status_message input in dropdown (max 128 chars, save on
  blur/Enter), subtitle uses same precedence as peer view
- AuthContext: auto-flip offline → online on session mount; best-effort
  offline on beforeunload/pagehide; respects explicit idle/dnd/invisible
- i18n: presence.status_placeholder (DE + EN)

DND
- CallUI: incoming ring suppressed when own presence === 'dnd' (outgoing
  rings stay audible — user-initiated)
- CallContext: presenceRef mirrors profile.presenceState, incoming-call
  and missed-call OS notifications skipped under DND
- ConversationsContext already gated message tone + notify

Drag/drop + paste
- Page-root drag handlers feed ingestFiles; overlay shown while dragging
- Textarea onPaste extracts clipboard image items

@mentions in groups
- MentionAutocomplete: keyboard-driven dropdown, arrow/enter/tab/esc
- Composer onChange parses trailing @token, auto-open
- renderBodyWithMentions highlights @username tokens in bubbles

Link previews
- Migration 20260421000003_link_previews.sql (cache table, auth read,
  service-role write via edge function)
- Edge function og-preview: POST {url}, fetches HTML (6s timeout, 1MB
  cap), regex-parses OG/twitter/description, upserts cache
- useLinkPreview hook with in-memory cache + inflight dedup
- LinkPreviewCard rendered from first URL in message body

Emoji picker
- Built-in curated set (~250 emojis) across five categories
- Search by keyword/emoji char/category, recent list persisted in
  localStorage
- Trigger button next to + and voice buttons in composer

Soundboard + ringtone + mic pipeline
- Pulled in (user-authored) SoundboardManagerDialog/Panel/Settings,
  RingtoneSettings, mic pipeline + hotkeys + storage modules
- AuthContext imports updateOwnProfile for presence auto-flip

Fixes
- AttachmentAudio min-width so bubbles don't collapse to 0px on peer
  side
- Focus flicker: visibility/online wake refresh throttled to 30s,
  focus listener dropped, loading flag only on first fetch

apps/desktop/src/components/MessageBubble.tsx

@@ -13,8 +13,13 @@ import { useAuth } from '../context/AuthContext';
 import { devLocalSecretStore } from '../lib/secretStore';
 import { supabase } from '../lib/supabase';
 import type { AggregatedReaction } from '../lib/useMessageReactions';
+import { extractFirstUrl } from '../lib/useLinkPreview';
 import { AttachmentAudio } from './AttachmentAudio';
+import { AttachmentGeneric } from './AttachmentGeneric';
 import { AttachmentImage } from './AttachmentImage';
+import { AttachmentPdf } from './AttachmentPdf';
+import { AttachmentVideo } from './AttachmentVideo';
+import { LinkPreviewCard } from './LinkPreviewCard';
 import { Avatar } from './Avatar';
 import { ForwardIcon, PencilIcon, PhoneIcon, PhoneOffIcon, ReplyIcon, SmileIcon, SpinnerIcon, TrashIcon, XIcon } from './icons';
 
@@ -299,14 +304,27 @@ export function MessageBubble({
               <span className="italic opacity-70">…cannot decrypt</span>
             ) : (
               <>
-                {bodyText.length > 0 && <div>{bodyText}</div>}
-                {attachments.map((a) =>
-                  a.mimeType.startsWith('audio/') ? (
-                    <AttachmentAudio key={a.id} handle={a} />
-                  ) : (
-                    <AttachmentImage key={a.id} handle={a} />
-                  ),
-                )}
+                {bodyText.length > 0 && <div>{renderBodyWithMentions(bodyText)}</div>}
+                {bodyText.length > 0 &&
+                  (() => {
+                    const url = extractFirstUrl(bodyText);
+                    return url ? <LinkPreviewCard url={url} /> : null;
+                  })()}
+                {attachments.map((a) => {
+                  if (a.mimeType.startsWith('audio/')) {
+                    return <AttachmentAudio key={a.id} handle={a} />;
+                  }
+                  if (a.mimeType.startsWith('image/')) {
+                    return <AttachmentImage key={a.id} handle={a} />;
+                  }
+                  if (a.mimeType.startsWith('video/')) {
+                    return <AttachmentVideo key={a.id} handle={a} />;
+                  }
+                  if (a.mimeType === 'application/pdf') {
+                    return <AttachmentPdf key={a.id} handle={a} />;
+                  }
+                  return <AttachmentGeneric key={a.id} handle={a} />;
+                })}
               </>
             )}
             <div
@@ -510,6 +528,33 @@ function formatDuration(totalSec: number): string {
   return m + ':' + s.toString().padStart(2, '0');
 }
 
+// Splits body text on `@username` tokens, rendering matches as highlighted
+// pills. Username alphabet matches Supabase citext usernames: alphanumerics
+// + underscores, length 1..32 (we don't bound here — regex is permissive
+// and keys off a leading `@` with an alnum/underscore follow).
+const MENTION_RE = /@([A-Za-z0-9_]{1,32})/g;
+
+function renderBodyWithMentions(text: string): React.ReactNode[] {
+  const out: React.ReactNode[] = [];
+  let lastIdx = 0;
+  let m: RegExpExecArray | null;
+  MENTION_RE.lastIndex = 0;
+  while ((m = MENTION_RE.exec(text)) !== null) {
+    if (m.index > lastIdx) out.push(text.slice(lastIdx, m.index));
+    out.push(
+      <span
+        key={m.index + ':' + m[1]}
+        className="rounded bg-accent/20 px-1 text-accent"
+      >
+        {m[0]}
+      </span>,
+    );
+    lastIdx = m.index + m[0].length;
+  }
+  if (lastIdx < text.length) out.push(text.slice(lastIdx));
+  return out;
+}
+
 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.