feat(embeds): fullscreen, wider cards, Instagram/Tidal/Reddit; fix TikTok/X/Twitch

Feedback fixes + new platforms:
- Fullscreen: add a universal 'Fullscreen' button on video embeds (requests
  fullscreen on the media container) so Shorts/TikTok/etc. can go fullscreen
  regardless of each player's own controls. Portrait media enlarged (220->300).
- Drop the iframe sandbox (CSP-allowlisted trusted hosts; sandbox was breaking
  player features and likely TikTok).
- Wider, responsive embed/tweet cards (min(34rem,92vw)) so Twitch player chrome
  isn't cramped and X posts stop getting clipped.
- Instagram (p/reel/tv), Tidal (track/album/playlist/video), and Reddit posts
  now embed. Reddit uses redditmedia.com to bypass the homeserver's blocked
  preview (Reddit serves it a bot-check 'please wait for verification' page);
  a bot-wall title filter keeps that garbage out of any caption.

New pure parsers unit-tested (videoEmbed.test.ts, 17 cases). Desktop + live web
CSP frame-src updated for instagram.com, embed.tidal.com, redditmedia.com.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/utils/videoEmbed.ts

@@ -3,9 +3,10 @@
 //
 // "kind" drives how the card lays the embed out:
 //   landscape → 16:9 video      portrait → 9:16 video
-//   audio     → short fixed-height player (Spotify/SoundCloud)
+//   audio     → short fixed-height player (Spotify/SoundCloud/Tidal/Apple Music)
+//   rich      → tall fixed-height post embed (Instagram / Reddit)
 
-export type EmbedKind = 'landscape' | 'portrait' | 'audio';
+export type EmbedKind = 'landscape' | 'portrait' | 'audio' | 'rich';
 
 export type MediaEmbed = {
   provider: string;
@@ -201,6 +202,62 @@ export function getTweetId(url: string): string | null {
   }
 }
 
+// --- Tidal ----------------------------------------------------------------
+
+export function getTidalEmbed(
+  url: string,
+): { kind: 'audio' | 'landscape'; embedUrl: string; height?: number } | null {
+  try {
+    const u = new URL(url);
+    const h = u.hostname.replace(/^(www|listen|desktop)\./, '');
+    if (h !== 'tidal.com') return null;
+    const p = u.pathname.replace(/^\/browse/, '');
+    let m = p.match(/^\/track\/(\d+)/);
+    if (m) return { kind: 'audio', embedUrl: `https://embed.tidal.com/tracks/${m[1]}`, height: 120 };
+    m = p.match(/^\/album\/(\d+)/);
+    if (m) return { kind: 'audio', embedUrl: `https://embed.tidal.com/albums/${m[1]}`, height: 400 };
+    m = p.match(/^\/playlist\/([0-9a-fA-F-]+)/);
+    if (m)
+      return { kind: 'audio', embedUrl: `https://embed.tidal.com/playlists/${m[1]}`, height: 400 };
+    m = p.match(/^\/video\/(\d+)/);
+    if (m) return { kind: 'landscape', embedUrl: `https://embed.tidal.com/videos/${m[1]}` };
+  } catch {
+    /* ignore */
+  }
+  return null;
+}
+
+// --- Instagram ------------------------------------------------------------
+
+export function getInstagramEmbed(url: string): string | null {
+  try {
+    const u = new URL(url);
+    if (u.hostname !== 'instagram.com' && u.hostname !== 'www.instagram.com') return null;
+    const m = u.pathname.match(/^\/(p|reel|reels|tv)\/([A-Za-z0-9_-]+)/);
+    if (!m) return null;
+    const type = m[1] === 'reels' ? 'reel' : m[1];
+    return `https://www.instagram.com/${type}/${m[2]}/embed/`;
+  } catch {
+    return null;
+  }
+}
+
+// --- Reddit (post embed via redditmedia — bypasses the homeserver's blocked
+//     preview fetch, which Reddit serves a bot-check "please wait" page to) ---
+
+export function getRedditPostEmbed(url: string): string | null {
+  try {
+    const u = new URL(url);
+    const h = u.hostname.replace(/^(www|old|new|np|i)\./, '');
+    if (h !== 'reddit.com') return null;
+    const m = u.pathname.match(/^\/r\/([A-Za-z0-9_]+)\/comments\/([A-Za-z0-9]+)/);
+    if (!m) return null;
+    return `https://www.redditmedia.com/r/${m[1]}/comments/${m[2]}/?ref_source=embed&ref=share&embed=true&theme=dark`;
+  } catch {
+    return null;
+  }
+}
+
 // --- Embed-URL builders ---------------------------------------------------
 
 const enc = encodeURIComponent;
@@ -294,5 +351,15 @@ export function parseMediaEmbed(url: string, host: string): MediaEmbed | null {
       height: apple.height,
     };
 
+  const tidal = getTidalEmbed(url);
+  if (tidal)
+    return { provider: 'tidal', kind: tidal.kind, embedUrl: tidal.embedUrl, height: tidal.height };
+
+  const insta = getInstagramEmbed(url);
+  if (insta) return { provider: 'instagram', kind: 'rich', embedUrl: insta, height: 720 };
+
+  const reddit = getRedditPostEmbed(url);
+  if (reddit) return { provider: 'reddit', kind: 'rich', embedUrl: reddit, height: 480 };
+
   return null;
 }