Add named keyboard binding modes (#32)

Add named keyboard shortcut maps with an Escape exit and a panel indicator. Keep press/release ownership across transitions, validate remapped Escape keys, and cancel stale repeats and focus previews.

Give the indicator ownership of the panel while a mode is active. Close popovers, collapse Morph, and keep Live Activities data current without resizing the hidden panel. Document configuration and transition behavior.

Validation: 1,519 workspace Rust tests passed; 70 Python tests passed. Workspace build, formatting, Clippy, and Settings configuration validation passed. Opt-in native desktop checks were not rerun because Weston is absent.

Related: #5.

compositor/src/session_lock.rs

@@ -434,6 +434,7 @@ impl SessionLockHandler for Ferese {
         // Replacing an orphan never passes through Unlocked. Existing protected
         // presentation facts remain valid, but old surfaces must not own input.
         self.session_lock.lifecycle = Lifecycle::Acquiring(confirmation);
+        self.set_binding_mode("default");
         self.capture_epoch = self.capture_epoch.wrapping_add(1);
         self.session_lock.surfaces.clear();
         self.cancel_logout_confirmation();
@@ -472,7 +473,6 @@ impl SessionLockHandler for Ferese {
         let keyboard = self.seat.get_keyboard().unwrap();
         keyboard.unset_grab(self);
         keyboard.set_focus(self, None, serial);
-        self.intercepted_keys.clear();
         self.lock_input_activity();
         self.confirm_lock_if_ready();
         crate::backends::direct::render_all(self);