Add export button for channel data and update API integration

Co-authored-by: Copilot <copilot@github.com>

webui/app.js

@@ -84,6 +84,14 @@ function renderChannels(channels) {
       await refreshDashboard();
     });
 
+    node.querySelector(".export-btn").addEventListener("click", async () => {
+      await api("/api/jobs/export-channel", {
+        method: "POST",
+        body: JSON.stringify({ channel_id: channel.channel_id }),
+      });
+      await refreshDashboard();
+    });
+
     node.querySelector(".export-view-btn").addEventListener("click", () => {
       window.location.href = `/viewer?channel=${encodeURIComponent(channel.channel_id)}`;
     });

webui/index.html

@@ -194,8 +194,7 @@
         <td class="last-date"></td>
         <td>
           <div class="action-row">
-            <button class="button button-small scrape-btn">Scrape</button>
-            <button class="button button-small export-view-btn">Viewer</button>
+            <button class="button button-small scrape-btn">Scrape</button>            <button class="button button-small export-btn">Export</button>            <button class="button button-small export-view-btn">Viewer</button>
             <button class="button button-small media-btn">Rescrape media</button>
             <button class="button button-small danger remove-btn">Удалить</button>
           </div>