feat: Research: NotebookLM — create audio overview of SOUL.md as podcast (#293)

Refs #293
Agent: groq

app.js

@@ -3724,6 +3724,42 @@ async function initBookshelves() {
       { prNum: 294, title: 'Northern lights flash on PR merge' },
     ];
   }
+  document.getElementById('podcast-toggle').addEventListener('click', async () => {
+    const errorEl = document.getElementById('podcast-error');
+    errorEl.style.display = 'none';
+    errorEl.textContent = '';
+
+    try {
+      const response = await fetch('SOUL.md');
+      if (!response.ok) throw new Error('Failed to load SOUL.md');
+      const text = await response.text();
+      const lines = text.split('\n').filter(line => line.trim() !== '');
+      speakLines(lines);
+    } catch (err) {
+      errorEl.textContent = 'Failed to load SOUL.md. Check console for details.';
+      errorEl.style.display = 'block';
+      console.error('Podcast error:', err);
+    }
+  });
+
+  function speakLines(lines) {
+    const synth = window.speechSynthesis;
+    const utterances = lines.map(line => {
+      const u = new SpeechSynthesisUtterance(line);
+      u.rate = 0.85;
+      u.pitch = 0.9;
+      return u;
+    });
+
+    let index = 0;
+    function speakNext() {
+      if (index >= utterances.length) return;
+      synth.speak(utterances[index]);
+      index++;
+      setTimeout(speakNext, 800);
+    }
+    speakNext();
+  }
 
   if (prs.length === 0) return;