Do users want session restore?

[cheerfulScumbag]

I have already built an opt-in implementation in PR (#800).
When enabled, it:

• saves open windows on a clean shutdown
• relaunches supported applications
• restores their tags and outputs
• restores floating, fullscreen, and geometry state

I have tested the implementation and it works, but the PR has become large because Mango currently has
no session-management framework. It therefore has to handle everything itself: finding launch commands,
matching reopened windows, saving the session, and restoring Mango’s window state.

Since I opened the PR, xdg-session-management-v1
(https://gitlab.freedesktop.org/wayland/wayland-protocols/-/blob/main/staging/xdg-session-management/xdg-session-management-v1.xml)
has entered Wayland’s staging protocols. Its compositor side is already implemented by KWin and Mutter.

This could give Mango a standardised Wayland foundation for identifying application sessions and
restoring windows before they map, rather than relying entirely on Mango-specific matching.

I am willing to continue working on this in whichever form makes the most sense for Mango:

• continue improving the existing PR; or
• work with maintainers and contributors to add xdg-session-management-v1, then restructure the
  session-restore work around that foundation

I have already put significant work into this feature and would like to continue. Before investing in
the next stage, however, I need to know whether it would be useful to other Mango users or whether I am
mainly building it for myself.

@DreamMaoMao, if Mango users want session restore, would you be open to either of these directions
becoming part of Mango? I would appreciate some guidance on the preferred approach.