Highlight matching structures on UnitDisplay hover

Wires the existing ToggleStructureEvent (emitted on UnitDisplay button
mouseenter/leave) to view.setHighlightStructureTypes via a small
StructureHighlightController. StructurePass + StructureLevelPass already
implement the highlight visual — this just connects the two ends.

src/client/hud/GameRenderer.ts

@@ -7,6 +7,7 @@ import { TransformHandler } from "../TransformHandler";
 import { UIState } from "../UIState";
 import { BuildPreviewController } from "../controllers/BuildPreviewController";
 import { HoverHighlightController } from "../controllers/HoverHighlightController";
+import { StructureHighlightController } from "../controllers/StructureHighlightController";
 import { WarshipSelectionController } from "../controllers/WarshipSelectionController";
 import { GameView as WebGLGameView } from "../render/gl";
 import { FrameProfiler } from "./FrameProfiler";
@@ -272,6 +273,7 @@ export function createRenderer(
     new WarshipSelectionController(game, eventBus, transformHandler, view),
     new BuildPreviewController(game, eventBus, uiState, transformHandler, view),
     new HoverHighlightController(game, eventBus, transformHandler, view),
+    new StructureHighlightController(eventBus, view),
     new AttackingTroopsOverlay(game, transformHandler, eventBus, userSettings),
     eventsDisplay,
     actionableEvents,