Advanced permissions UI: users with numeric IDs are not searchable

Bug description

In the "Advanced permissions for Team folder" UI, searching for users with numeric user IDs (e.g. 100011011, 100000898) returns no results, even when those users are members of the group assigned to the Team folder.

Searching by display name (e.g. Japanese name like "Shimizu / 清水") also returns no results for these users.

Users with string-based IDs (e.g. sato_user) are searchable normally.

Steps to reproduce

1. Have users with numeric IDs (e.g. imported from external directory) as members of a group assigned to a Team folder
2. Open a subfolder inside the Team folder
3. Open the sharing sidebar → "Advanced permissions for Team folder"
4. Type a partial numeric ID (e.g. 10) or the user's display name in the search box
5. Observe: "No results" is shown

Expected behavior

Users should be searchable by either:

• Their user ID (including numeric IDs with partial match)
• Their display name

Actual behavior

• Numeric IDs: not found even with partial match (e.g. 10 does not match 100000898)
• Non-ASCII display names (e.g. Japanese): not found at all
• String IDs (e.g. sato_user): found correctly via prefix match

Workaround

• Opening the dropdown without typing shows a scrollable list of all users
• Using occ groupfolders:permissions command works correctly

Environment

• Nextcloud version: 33.0.2
• Group Folders app version: (please check)
• User backend: local users with numeric IDs
• Browser: Chrome (latest)
• Server OS: Ubuntu 24.04 LTS

Start at the Advanced permissions for Team folder sharing sidebar described in the reproduction steps, and reproduce searches for a partial numeric ID, a Japanese display name, and a string ID. Trace the UI search entry point and its user-list response, then verify that the expected users appear while the existing string-ID behavior remains intact.