fix: consolemode://stop and Start + Select close Big Picture / Playnite before restoring

[nextestudios]

Summary

Leaving console mode from outside the session — consolemode://stop, or holding Start + Select — restored the monitors but left the front-end running, so Big Picture ended up on the desk monitor and had to be closed by hand.

Now those requests close the front-end first:

• LaunchService.CloseFrontEnd: Big Picture via Steam's own steam://close/bigpicture (back to the desktop client), Playnite via CloseMainWindow; if still there halfway through, WM_CLOSE on its window.
• MainViewModel.StopConsoleAsync: after closing it, the existing loop notices the exit and restores the desk on its own — the same path as when you exit Big Picture yourself — and it restores explicitly only if console mode is still active.
• Xbox mode has no window of its own: it just restores, as before.
• The tray's Restore is unchanged (restores only).
• README (EN/PT) mentions it on the automation line.

Validation

• Release workflow in build-only mode on this branch alone: installer + portable build, dotnet test 61 passed.
• Independent of feat: local control API (named pipe) — status, plus consolemode:// actions with a reply #24; applies on current main.

🤖 Generated with Claude Code

[lippdev]

Thanks for this one, closing Big Picture / Playnite before restoring is a real gap. It needs a few adjustments before it can go in:

1. Rebase on main. It conflicts in App.xaml.cs and README.md. The README was slimmed down since: the automation line now lives in docs/GUIDE.md and docs/GUIDE.pt-BR.md, so please move the note about stop there instead.
2. The wait in StopConsoleAsync is shorter than a real restore. It polls IsConsoleActive for 12 × 500 ms = 6 s, but a restore on a three-screen setup took about 9 s in the log. After the 6 s it calls RestoreNowAsync() while the restore started by the loop is still running. Engine.Stop() returns at once because of RestoreInProgress, so IsConsoleActive is set to false and the "restored" status is shown before the desk is actually back (and ReloadAsync() reads the screens mid-restore). Please also wait while Engine.State.RestoreInProgress is true (with a longer cap, say 30 s), and only restore explicitly if nothing is restoring.
3. A product question: Start + Select now also quits Big Picture. Until now it only went back to the PC. If that is the intent, keep it, but please confirm that the session menu's Back to the PC still restores only, and Exit Console Mode is the one that exits.
4. Conventions (see AGENTS.md): a changelog entry under ## [Unreleased] in both CHANGELOG.md and CHANGELOG.en-US.md, ending with the PR number, and a manual check in docs/TESTING.md (closing Big Picture and Playnite from consolemode://stop and from the chord).

CI now builds and tests on Windows for every PR, so you will see the result here after the rebase.