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.

shell/ferese-shell/src/activities.rs

@@ -381,15 +381,17 @@ impl FereseShell {
             }
             // Compact ranking changes must not replay the expanded panel's
             // crossfade: its live rows update in place, preserving focus/scroll.
-            if before != runtime.activities.selection.visible
-                && matches!(
-                    runtime.hub.mode(),
-                    ferese_panel::morph::Mode::Idle | ferese_panel::morph::Mode::Peek
-                )
-            {
-                runtime.hub.replace_content();
+            if self.snapshot.binding_mode.is_none() {
+                if before != runtime.activities.selection.visible
+                    && matches!(
+                        runtime.hub.mode(),
+                        ferese_panel::morph::Mode::Idle | ferese_panel::morph::Mode::Peek
+                    )
+                {
+                    runtime.hub.replace_content();
+                }
+                runtime.refresh_activity_size();
             }
-            runtime.refresh_activity_size();
         }
     }
     pub fn activity_tick_subscription(&self) -> Subscription<()> {