Add in-app debug log panel

frontend/index.html

@@ -74,6 +74,25 @@
       </section>
     </main>
 
+    <button id="debugToggle" class="fixed bottom-4 right-4 z-40 rounded-full border border-white/15 bg-black/70 px-4 py-2 text-xs uppercase tracking-[0.25em] text-zinc-300 backdrop-blur">
+      Logs
+    </button>
+
+    <aside id="debugPanel" class="fixed bottom-4 right-4 z-40 hidden h-[60vh] w-[min(92vw,720px)] overflow-hidden rounded-3xl border border-white/10 bg-zinc-950/95 shadow-2xl backdrop-blur">
+      <div class="flex items-center justify-between border-b border-white/10 px-4 py-3">
+        <div>
+          <p class="text-[11px] uppercase tracking-[0.25em] text-zinc-500">Developer Logs</p>
+          <p id="debugSummary" class="text-sm text-zinc-300">No events yet</p>
+        </div>
+        <div class="flex items-center gap-2">
+          <button id="downloadLogs" class="rounded-full border border-white/10 px-3 py-2 text-xs uppercase tracking-[0.2em] text-zinc-300">Download .log</button>
+          <button id="clearLogs" class="rounded-full border border-white/10 px-3 py-2 text-xs uppercase tracking-[0.2em] text-zinc-300">Clear</button>
+          <button id="closeDebugPanel" class="rounded-full border border-white/10 px-3 py-2 text-xs uppercase tracking-[0.2em] text-zinc-300">Close</button>
+        </div>
+      </div>
+      <div id="debugLogList" class="h-[calc(60vh-78px)] overflow-auto px-3 py-3 font-mono text-xs text-zinc-200"></div>
+    </aside>
+
     <div id="previewModal" class="fixed inset-0 z-50 hidden items-center justify-center bg-black/80 px-4">
       <div class="w-full max-w-5xl rounded-3xl border border-white/10 bg-zinc-950 p-5 shadow-2xl">
         <div class="flex items-start justify-between gap-4">
@@ -144,6 +163,6 @@
       </a>
     </template>
 
-    <script src="/app.js?v=20260313h" defer></script>
+    <script src="/app.js?v=20260313i" defer></script>
   </body>
 </html>