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/pages/SettingsPage.tsx

@@ -9,6 +9,8 @@ import { useTranslation } from 'react-i18next';
 
 import { Avatar } from '../components/Avatar';
 import { BackupExportDialog } from '../components/BackupExportDialog';
+import { RingtoneSettings } from '../components/RingtoneSettings';
+import { SoundboardSettings } from '../components/SoundboardSettings';
 import { LockIcon } from '../components/icons';
 import { useAuth } from '../context/AuthContext';
 import { useCall } from '../context/CallContext';
@@ -141,6 +143,16 @@ export function SettingsPage() {
         />
       </Section>
 
+      {/* Ringtone (incoming custom) */}
+      <Section title={t('app:settings.section_ringtone', { defaultValue: 'Klingelton' })}>
+        <RingtoneSettings disabled={busy} />
+      </Section>
+
+      {/* Soundboard */}
+      <Section title={t('app:settings.section_soundboard', { defaultValue: 'Soundboard' })}>
+        <SoundboardSettings />
+      </Section>
+
       {/* Voice / Push-to-Talk + Audio Quality + E2EE */}
       <Section title={t('app:settings.section_voice', { defaultValue: 'Sprache' })}>
         <AudioDeviceControls />