perf: several dragged items cross to another place as one tar stream; older agents get them one by one

internal/server/web/static/dnd.js

@@ -155,14 +155,18 @@
       q('.dd-ptext').textContent = 'подготовка…';
       q('.dd-cancel').textContent = 'Стоп';
     }
-    for (const p of item.paths) {
+    // Between places, all of them go as one stream: the first, and the rest
+    // as "more" (the server sends one by one to older agents).
+    const batch = here ? item.paths.map(p => [p]) : [item.paths];
+    for (const group of batch) {
+      const p = group[0];
       if (c.stop) break;
       const name = p.split('/').pop();
       let r;
       if (here) {
         r = await from.src.op('copy', {src: p, dst: join(t.dir, name), move: isMove, conflict});
       } else {
-        const body = {src: p, name, dir: t.dir, conflict, move: isMove};
+        const body = {src: p, name, dir: t.dir, conflict, move: isMove, more: group.slice(1)};
         if (t.source.kind === 'ssh') { body.to = t.pane.agent.id; body.to_conn = t.pane.src.conn; }
         else body.to = t.pane.agent.id;
         if (from.kind === 'sshfiles') body.from_conn = from.src.conn;
@@ -170,7 +174,7 @@
         r = await new MachineSource(from.agent).op('ship', body);
         if (r.ok) {
           c.job = r.data.job;
-          const pre = item.paths.length > 1 ? name + ': ' : '';
+          const pre = '';
           r = await FV.followJob(c.job, (pr, text) => {
             if (pr.total > 0 || pr.done > 0) {
               q('.dd-bar').parentNode.classList.remove('wait');
@@ -182,7 +186,7 @@
         }
       }
       if (!r.ok) { err = r.error || 'ошибка'; break; }
-      done++;
+      done += group.length;
       skipped += (r.data && r.data.skipped) || 0;
     }
     close();