feat(cockpit): teleport the shared Display groups into Cockpit's popover

The Cockpit display portal publishes the Display popover's slots to the
gev-display store while Cockpit is on, and the Display panel teleports its
HUD, Detection, Parameters and 3D groups into them and back, each only
while its own slot is published. The portal no longer moves the groups:
it keeps each surface's scroll position, puts back focus the move
dropped, and lays the surfaces out once Vue has moved them. The popover's
uses-shared-display-controls class renders from the store, and the right
rail no longer re-homes the parameters panel the markup already places.

docs/VUE-MIGRATION.md

@@ -329,8 +329,11 @@ a feature supplying only its accent.
    `CockpitUtilityControls` renders the Display
    and Radio launchers, which popover is open and the compact Radio
    controls from the `gev-radio` store that RadioControls publishes to and
-   answers through; the Display popover's slots stay static for the Cockpit
-   display portal).
+   answers through. The Cockpit display portal publishes the Display
+   popover's slots to the `gev-display` store while Cockpit is on, and
+   `DisplayPanel` teleports its HUD, Detection, Parameters and 3D groups into
+   them and back; the portal keeps each surface's scroll position and puts
+   back focus the move dropped).
    Layers that write into the right rail directly gain a slot instead.
 
 4. **Cleanup.** The build-time template expansion is retired: `index.html`