Web: redesign, logo, PWA, QR codes, Spotify guidance

- Album-art-tinted cards that crossfade on song change, equalizer bars,
  live avatar rings, drifting ambient colour, Space Grotesk display font,
  brand purple-to-blue gradient from the logo
- Feed cards rise in and glide to new positions (motion); respects
  reduced-motion
- New logo as nav mark, favicon and Apple touch icon
- Installable PWA: manifest, maskable icons, small service worker
  (cached build assets + offline page), security headers
- Show-QR-code on your own profile; centred profile header with stats
- Settings explains connecting Spotify via Last.fm or ListenBrainz

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/web/public/offline.html

@@ -0,0 +1,38 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <meta name="theme-color" content="#07070b" />
+    <title>musicshare · offline</title>
+    <style>
+      body {
+        margin: 0;
+        min-height: 100vh;
+        display: grid;
+        place-items: center;
+        background: radial-gradient(circle at 20% 10%, #3b1170 0, transparent 45%),
+          radial-gradient(circle at 90% 90%, #0f3f86 0, transparent 50%), #07070b;
+        color: #f4f3fa;
+        font: 16px/1.5 ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
+        text-align: center;
+        padding: 1.5rem;
+      }
+      img { width: 88px; height: 88px; border-radius: 22px; }
+      h1 { font-size: 1.6rem; margin: 1rem 0 0.4rem; }
+      p { color: #9b99ae; margin: 0 0 1.5rem; }
+      button {
+        font: inherit; font-weight: 600; color: #fff; border: 0; border-radius: 999px; padding: 0.7rem 1.4rem; cursor: pointer;
+        background: linear-gradient(135deg, #7b2ff7, #5b4cf0, #2f8cff);
+      }
+    </style>
+  </head>
+  <body>
+    <main>
+      <img src="/icon-192.png" alt="" />
+      <h1>You're offline</h1>
+      <p>musicshare needs a connection to see what your friends are playing.</p>
+      <button onclick="location.reload()">Try again</button>
+    </main>
+  </body>
+</html>