404 on https://cryptpad.fr/kanban/templates.js?ver=2026.5.1-11

### Description

I think maybe my browser cached an old reference to that file from May. (oh wait actually 2026.5 is the newest? I'm not sure.)

I hit this while trying to do "Make a copy" on a Kanban board. Disabling my browser cache temporarily in the dev tools seems to work around it.

### Steps to reproduce

1. Have stuff in your cache?
2. Open a Kanban board
3. Hit "Make a copy"
4. A new tab opens and hangs at "Load Drive"

### Relevant logs

```shell

```

### Expected behavior

Expected the loading bar to continue and show the new copy. If I disable cache it does.

### Which operating system are you using?

Linux/BSD/UNIX

### What browsers are you seeing the problem on?

Mozilla Firefox

### Extensions

I have uBlock Origin I think. It came with LibreWolf.

### Version

Other

Start by reproducing the Kanban “Make a copy” flow in Firefox with a populated cache, then inspect the request for https://cryptpad.fr/kanban/templates.js?ver=2026.5.1-11 and the point where the new tab hangs at “Load Drive.” Trace why the cached asset returns 404, and consider the issue done when a cached browser can complete the copy and show the new board.

Written by the indexing model from the issue text.