Feat: Implement playlist download count tracking during downloads with UI updates

public/index.html

@@ -265,6 +265,7 @@
                 <div style="display: flex; gap: 20px; align-items: center;">
                     <div id="downloadProgressText"></div> 
                     <div id="downloadSpeedText"></div>
+                    <div id="playlistInfoText" style="display: none; font-size: 0.9rem;"></div>
                     <button type="button" id="stopBtn" onclick="stopDownload()" class="stop-btn" style="display:none;" title="Stop download">■</button>
                 </div>
             </div>

public/script/downloadstatus.js

@@ -118,4 +118,7 @@ function resetProgressBar() {
 
   const speedElement = document.getElementById("downloadSpeedText");
   if (speedElement) speedElement.style.display = "none";
+
+  const playlistInfoElement = document.getElementById("playlistInfoText");
+  if (playlistInfoElement) playlistInfoElement.style.display = "none";
 }

public/script/progressBar.js

@@ -4,8 +4,10 @@ const progressBarText = document.getElementById("downloadProgressText")
 
 const speedElement = document.getElementById("downloadSpeedText");
 const stageElement = document.getElementById("downloadStage");
+const playlistInfoElement = document.getElementById("playlistInfoText");
 const speedEvt = new EventSource("/download/speed");
 const stageEvt = new EventSource("/download/stage");
+const playlistInfoEvt = new EventSource("/download/playlist-info");
 
 function startProgress() {
   progressBar.style.width = "0%";
@@ -45,6 +47,9 @@ function resetProgress() {
   stageElement.textContent = "";
   stageElement.style.display = "none";
 
+  playlistInfoElement.textContent = "";
+  playlistInfoElement.style.display = "none";
+
   // Hide stop button
   const stopBtn = document.getElementById("stopBtn");
   if (stopBtn) stopBtn.style.display = "none";
@@ -85,4 +90,9 @@ speedEvt.onmessage = e => {
 stageEvt.onmessage = e => {
   stageElement.style.display = "block";
   stageElement.textContent = e.data; // ex: "📥 Downloading..."
+};
+
+playlistInfoEvt.onmessage = e => {
+  playlistInfoElement.style.display = "block";
+  playlistInfoElement.textContent = e.data; // ex: "Item 1 of 15"
 };