test(core): интеграция Settings/Power на session-шине (#[ignore])

Settings round-trip + Changed; Power state + fake-ACC AccChanged — на живой D-Bus.
just test-integration (dbus-run-session). #[ignore] → just ci (unit) не требует шины.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Alexander <akotenev2003@gmail.com>

Cargo.toml

@@ -30,4 +30,5 @@ thiserror = "1"
 clap = { version = "4", features = ["derive"] }
 # dev
 tempfile = "3"
+futures-util = "0.3"
 # slint — добавляется в Плане 4 (вместе с slint GPL-3.0 exception в deny.toml)