Give touch-opened OnDemand layers keyboard focus

Remember and consume the opening interaction instead of depending on pointer focus. Revoke pending focus after another interaction, focus change, cancellation or unmapping, and retain lock and grab safeguards.

Fixes #54

compositor/src/state.rs

@@ -470,6 +470,7 @@ pub struct Ferese {
     pub(crate) tab_indicator_settings: crate::config::TabIndicatorSettings,
     pub(crate) tab_bars: HashMap<WorkspaceId, Vec<ferese_layout::TabBar>>,
     pub(crate) consumed_pointer_buttons: HashSet<u32>,
+    pub(crate) pending_layer_focus: Option<(WlSurface, Instant)>,
     pub(crate) consumed_touch_slots: HashSet<smithay::backend::input::TouchSlot>,
     pub(crate) focus_history: ferese_core::FocusHistory,
     pub(crate) focus_cycle: Option<ferese_core::FocusCycle>,
@@ -785,6 +786,7 @@ impl Ferese {
             tab_indicator_settings: config.tab_indicator,
             tab_bars: HashMap::new(),
             consumed_pointer_buttons: HashSet::new(),
+            pending_layer_focus: None,
             consumed_touch_slots: HashSet::new(),
             focus_history: Default::default(),
             focus_cycle: None,