Use Linux native desktop notification buttons to confirm MFA prompts

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## Feature request
**Which Nextcloud Version are you currently using:** 3.17.0

**Is your feature request related to a problem? Please describe.**
When a new MFA (Multi-Factor Authentication) notification appears on Linux desktop environments (for example KDE), it only shows as a native desktop notification without any interactive buttons. Users currently have to manually open the Nextcloud desktop application to accept or deny the MFA request, which breaks the workflow and adds unnecessary friction to the authentication process.

**Describe the solution you'd like**
I would like the MFA desktop notifications to include interactive action buttons (e.g., "Accept" and "Deny") that allow users to respond to the authentication request directly from the notification popup. This would utilize the freedesktop.org notification specification's action support, as documented at https://specifications.freedesktop.org/notification-spec/latest/basic-design.html.

**Describe alternatives you've considered**
1. **Status quo**: Continue requiring users to open the main application GUI - this is cumbersome and interrupts workflow
2. **System tray context menu**: Could work but requires right-clicking and finding the option, which is less discoverable than notification buttons

**Additional context**
This feature could be useful for basically every notification that requires the user to interactively reply to the displayed text, for example accepting or rejecting a share received.