Option to hide Space sub-groups on the home screen

### Your use case

#### What would you like to do?

Add an option to hide sub-groups/rooms inside Spaces from the default home screen view, so only top-level Spaces are shown until a Space is opened.

#### Why would you like to do it?

Currently, all groups/rooms inside Spaces are visible directly on the home screen, which can become cluttered when using many Spaces.

This would provide:

* A cleaner and less overwhelming UI
* Easier navigation in large setups
* Better focus on the currently used Space
* A more compact and organized home screen

#### How would you like to achieve it?

Add a setting or toggle that collapses Space contents by default and only shows the rooms/sub-groups after opening the Space.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you willing to provide a PR?

No

No files, tests, or entry points are named. Start by locating the home-screen rendering for Spaces and the existing settings or toggle patterns; done means a setting can hide Space sub-groups on the default home screen while showing them after a Space is opened.

Written by the indexing model from the issue text.