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/lib/useLinkPreview.ts

@@ -0,0 +1,113 @@
+import { useEffect, useState } from 'react';
+
+import { supabase } from './supabase';
+
+export interface LinkPreview {
+  url: string;
+  title: string | null;
+  description: string | null;
+  imageUrl: string | null;
+  siteName: string | null;
+  ok: boolean;
+}
+
+// In-memory cache keyed by URL — avoids re-invoking the edge function for
+// the same URL within a session even if many bubbles reference it.
+const cache = new Map<string, LinkPreview | null>();
+const inflight = new Map<string, Promise<LinkPreview | null>>();
+
+async function loadPreview(url: string): Promise<LinkPreview | null> {
+  if (cache.has(url)) return cache.get(url)!;
+  const existing = inflight.get(url);
+  if (existing) return existing;
+
+  const p = (async () => {
+    // First try the cache table directly (RLS allows authenticated reads).
+    // Works offline-first if the server has already fetched this URL.
+    // `link_previews` is a later migration — cast around stale generated types.
+    const { data: cached } = await (supabase as unknown as {
+      from: (t: string) => {
+        select: (cols: string) => {
+          eq: (col: string, val: string) => {
+            maybeSingle: () => Promise<{
+              data: {
+                url: string;
+                title: string | null;
+                description: string | null;
+                image_url: string | null;
+                site_name: string | null;
+                ok: boolean;
+                fetched_at: string;
+              } | null;
+              error: Error | null;
+            }>;
+          };
+        };
+      };
+    })
+      .from('link_previews')
+      .select('url, title, description, image_url, site_name, ok, fetched_at')
+      .eq('url', url)
+      .maybeSingle();
+    if (cached && cached.ok) {
+      const preview: LinkPreview = {
+        url: cached.url,
+        title: cached.title,
+        description: cached.description,
+        imageUrl: cached.image_url,
+        siteName: cached.site_name,
+        ok: cached.ok,
+      };
+      cache.set(url, preview);
+      return preview;
+    }
+
+    try {
+      const { data, error } = await supabase.functions.invoke('og-preview', {
+        body: { url },
+      });
+      if (error) throw error;
+      const preview = data as LinkPreview | null;
+      cache.set(url, preview && preview.ok ? preview : null);
+      return cache.get(url) ?? null;
+    } catch {
+      cache.set(url, null);
+      return null;
+    }
+  })();
+
+  inflight.set(url, p);
+  try {
+    return await p;
+  } finally {
+    inflight.delete(url);
+  }
+}
+
+export function useLinkPreview(url: string | null): LinkPreview | null {
+  const [preview, setPreview] = useState<LinkPreview | null>(() =>
+    url ? cache.get(url) ?? null : null,
+  );
+  useEffect(() => {
+    if (!url) {
+      setPreview(null);
+      return;
+    }
+    let cancelled = false;
+    void loadPreview(url).then((p) => {
+      if (!cancelled) setPreview(p);
+    });
+    return () => {
+      cancelled = true;
+    };
+  }, [url]);
+  return preview;
+}
+
+// Regex tuned for plain URLs inside message text. No markdown link syntax yet.
+const URL_RE = /https?:\/\/[^\s<>"']+/i;
+
+export function extractFirstUrl(text: string): string | null {
+  const m = URL_RE.exec(text);
+  return m?.[0] ?? null;
+}