Currently, if installing flatpak fails, the entire installation fails. This can be problematic when the flatpak registry is unreliable or unavailable.

Similar to how insights-client registration failures are handled (see BZ-1931069), flatpak installation failures should not block the installation process.

Proposed Solution

Follow the same pattern used for insights-client (BZ-1931069):

• Display a clear error message when flatpak installation fails
• Allow the user to continue with the installation
• Users can install flatpaks manually later on the installed system

Acceptance Criteria

• When flatpak registry is unavailable or fails, show a clear error message to the user
• User can choose to continue the installation despite the flatpak failure
• Installation completes successfully without flatpaks