feat(demo): per-folder media merge + AIUI seed-chats bootstrap

- Curated files loader now MERGES per top-level folder: dropping real files into
  demo/files/Music/ swaps only Music and keeps the sample Documents/Photos/Videos
  (verified). Media plays with the Range support already in place.
- AIUI index.html: a ?seed bootstrap pre-loads the example "Content Showcase"
  conversation into AIUI's IndexedDB by calling the bundle's own
  seedPromptsToConversation() (identical to its /seed command), so the chat
  history isn't empty when the demo points users to "previous chats". Guarded by
  try/catch + an existence check; no-op without ?seed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

demo/aiui/index.html

@@ -14,6 +14,31 @@
     <link rel="icon" href="/aiui/favicon.svg" type="image/svg+xml" />
     <link rel="apple-touch-icon" href="/aiui/apple-touch-icon-180x180.png" />
     <title>AIUI</title>
+    <!-- Demo (?seed): pre-load the example "Content Showcase" conversation into
+         AIUI's IndexedDB so the chat history isn't empty (live chat is disabled
+         in the demo and points users to these previous chats). Mirrors the app's
+         own /seed exactly by calling its seedPromptsToConversation(). -->
+    <script type="module">
+      (async () => {
+        try {
+          if (!new URLSearchParams(location.search).has('seed')) return;
+          const db = await new Promise((res, rej) => {
+            const r = indexedDB.open('aiui-store', 1);
+            r.onupgradeneeded = (e) => { const d = e.target.result; if (!d.objectStoreNames.contains('conversations')) d.createObjectStore('conversations', { keyPath: 'id' }); };
+            r.onsuccess = () => res(r.result); r.onerror = () => rej(r.error);
+          });
+          const exists = await new Promise((res) => {
+            try { const q = db.transaction('conversations', 'readonly').objectStore('conversations').getKey('seed-all'); q.onsuccess = () => res(!!q.result); q.onerror = () => res(false); }
+            catch { res(false); }
+          });
+          if (exists) return;
+          const { seedPromptsToConversation } = await import('/aiui/assets/seedPrompts-CLWaUv28.js');
+          const conv = seedPromptsToConversation();
+          await new Promise((res, rej) => { const t = db.transaction('conversations', 'readwrite'); t.objectStore('conversations').put(conv); t.oncomplete = () => res(); t.onerror = () => rej(t.error); });
+          try { localStorage.setItem('aiui-active-conversation', conv.id); } catch {}
+        } catch (e) { console.warn('[demo] AIUI seed bootstrap failed', e); }
+      })();
+    </script>
     <script type="module" crossorigin src="/aiui/assets/index-Lh5NfTCq.js"></script>
     <link rel="stylesheet" crossorigin href="/aiui/assets/index-CHQ7uqBj.css">
   <link rel="manifest" href="/aiui/manifest.webmanifest"><script id="vite-plugin-pwa:register-sw" src="/aiui/registerSW.js"></script></head>

neode-ui/mock-backend.js

@@ -3626,11 +3626,21 @@ function loadDemoDiskFiles() {
   }
   walk(root, '/')
   if (!tree['/'].length) return // empty folder → keep the hardcoded seeds
-  for (const k of Object.keys(SEED_FILES)) delete SEED_FILES[k]
+  // Per-folder MERGE: a top-level folder present in demo/files replaces that
-  Object.assign(SEED_FILES, tree)
+  // seed folder; seed folders the curator didn't provide (e.g. sample Documents)
-  for (const k of Object.keys(SEED_FILE_CONTENTS)) delete SEED_FILE_CONTENTS[k]
+  // are kept. So dropping real Music/ doesn't wipe the sample Documents.
+  const provided = new Set(tree['/'].map(e => e.name))
+  for (const k of Object.keys(SEED_FILES)) {
+    if (k !== '/' && provided.has(k.split('/')[1])) delete SEED_FILES[k]
+  }
+  for (const k of Object.keys(SEED_FILE_CONTENTS)) {
+    if (provided.has(k.split('/')[1])) delete SEED_FILE_CONTENTS[k]
+  }
+  const keptRoot = (SEED_FILES['/'] || []).filter(e => !provided.has(e.name))
+  for (const [k, v] of Object.entries(tree)) { if (k !== '/') SEED_FILES[k] = v }
+  SEED_FILES['/'] = [...keptRoot, ...tree['/']]
   Object.assign(SEED_FILE_CONTENTS, contents)
-  console.log(`[Demo] Loaded curated files from demo/files (${Object.keys(diskFilePaths).length} binary, ${Object.keys(contents).length} text)`)
+  console.log(`[Demo] Merged curated files from demo/files (${Object.keys(diskFilePaths).length} binary, ${Object.keys(contents).length} text; folders: ${[...provided].join(', ')})`)
 }
 loadDemoDiskFiles()