Allow to enforce case insensitive filenames

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

due to a case sensitivity on the server, it'll accept one version over another, soft locking the desktop from downloading or merging the files.
example: Misc vs MISC
both can co exist in the server rather than being merged or aggregated

Steps to reproduce

1. client A creates a folder with an upper case name
2. client B creates a folder with a camel case name
3. desktop app will only download one due to OS restrictions, some file merging may be present but files will not be visible to the desktop client
   

Expected behavior

folders will merge, OR at least warn the desktop client that folder names are duplicated and should be resolved, throwing an error.
would like an aggregation function on the server

Installation method

Official All-in-One appliance

Nextcloud Server version

27

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

n/a

List of activated Apps

n/a

Nextcloud Signing status

n/a

Nextcloud Logs

n/a

Additional info

we are renting our server from an official partner. no technical details known.
I tried renaming folders locally but it causes the desktop app to crash on sync

Start by reproducing the case-variant folder scenario described in the issue with two clients, then trace how the server handles folder creation and how the desktop client receives duplicate names. The issue offers multiple possible outcomes—merging, warning, or an error—so the expected behavior must be decided before implementation and validation.