feat: drag files between file panes (move or copy, SSH hosts too) and into a terminal of the same machine

internal/server/web/templates/app.html

@@ -202,6 +202,7 @@
 <script src="{{asset "dbedit.js"}}"></script>
 <script src="{{asset "fileviews.js"}}"></script>
 <script src="{{asset "filepane.js"}}"></script>
+<script src="{{asset "dnd.js"}}"></script>
 <script src="{{asset "pages.js"}}"></script>
 <script src="{{asset "users.js"}}"></script>
 <script src="{{asset "account.js"}}"></script>