Office app does not show Collabora template previews unless hasPreview is set

Describe the bug
After upgrading to Nextcloud 34, the Office app shows Collabora document templates, but all template cards display only the generic document icon instead of preview images.

The preview URLs are generated and Collabora preview images are reachable, but the Office UI does not render them unless hasPreview is explicitly set to true in CollaboraTemplateProvider.

To Reproduce

1. Use Nextcloud 34 with richdocuments 11.0.0 and office 1.0.0.
2. Configure an external Collabora Online server.
3. Open the Office app.
4. Look at the template cards such as Syllabus, Resume, Letter, Invoice, etc.
5. All cards show generic icons instead of template preview images.

Expected behavior
Template cards should display their preview images.

Screenshots
Attached.

Client details:

• OS: Windows 11
• Browser: Chrome
• Version: 149
• Device: desktop

Server details

Operating system:
Docker deployment on ASUSTOR ADM v5

Web server:
nginx reverse proxy

Database:
MariaDB 11

PHP version:
PHP from official Nextcloud Docker image

Nextcloud version:
34.0.0.12

Version of the richdocuments app
11.0.0

Version of Collabora Online
26.04.1.4

Configuration of the richdocuments app
{
"apps": {
"richdocuments": {
"disable_certificate_verification": "",
"doc_format": "ooxml",
"edit_groups": "",
"enabled": "yes",
"installed_version": "11.0.0",
"public_wopi_url": "https://collabora.example.com/",
"types": "filesystem,prevent_group_restriction",
"use_groups": "",
"wopi_allowlist": "172.18.0.0/16",
"wopi_callback_url": "https://cloud.example.com/",
"wopi_url": "https://collabora.example.com/"
}
}
}

Start by locating CollaboraTemplateProvider and trace how its template data is passed to the Office template cards. Verify why preview URLs are ignored when hasPreview is not explicitly true, then confirm that the Syllabus, Resume, Letter, and Invoice cards render their preview images in the Office app.