A pasted tag containing a comma becomes two tags after reload #3710

Initial Checklist

• I understand this is a bug report and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

Bug Description

A pasted tag containing a comma becomes two tags after reload. Cause: packages/web-app-files/src/components/SideBar/Details/TagsSelect.vue:151-160: createOption doesn't split or reject commas (typing a comma is handled, pasting isn't).

Reproduction Steps

1. Paste red,blue into the tags field of a file and press Enter.
2. Reload.

Expected Outcome

Two tags, or a validation error.

Actual Outcome

One tag red,blue before reload, two tags after; the server stores a comma-separated list.