replace MapInteraction with HoverHighlightController; one input system

MapInteraction bound DOM events to the WebGL canvas, but the canvas has
pointer-events: none post-migration so its pointermove/down/up/wheel/
keydown listeners never fired — duplicating InputHandler (which owns
the inputOverlay div + EventBus pipeline) and leaving most features
dead. The one alive bit was hover→setHighlightOwner, which I'd
manually forwarded as a workaround.

Now there's a HoverHighlightController that listens to MouseMoveEvent,
computes the cursor's tile owner, and pushes setHighlightOwner. Delete
map-interaction.ts (418 lines) + keyboard-pan.ts, trim the DOM-binding
constructor + proxy methods (setFitZoomOnDoubleClick, setPanSpeed,
setZoomSpeed, etc.) out of GameView, and drop the ClientGameRunner
pointermove forwarder.

Input flows through one path: DOM → inputOverlay → InputHandler →
EventBus → controllers/renderer.

src/client/controllers/HoverHighlightController.ts

@@ -0,0 +1,44 @@
+/**
+ * HoverHighlightController — pushes the cursor's tile-owner to the WebGL
+ * view so the territory + border passes can highlight the hovered player.
+ *
+ * Replaces the hover path inside the renderer's MapInteraction class (which
+ * was bound to the WebGL canvas; that canvas has pointer-events: none in the
+ * current input architecture so its listeners never fired). All input flows
+ * through InputHandler → MouseMoveEvent on the EventBus, so we just listen.
+ */
+
+import { EventBus } from "../../core/EventBus";
+import { GameView } from "../../core/game/GameView";
+import { Controller } from "../Controller";
+import { MouseMoveEvent } from "../InputHandler";
+import { GameView as WebGLGameView } from "../render/gl";
+import { OWNER_MASK } from "../render/gl/utils/tile-codec";
+import { TransformHandler } from "../TransformHandler";
+
+export class HoverHighlightController implements Controller {
+  private lastOwnerID = 0;
+
+  constructor(
+    private game: GameView,
+    private eventBus: EventBus,
+    private transformHandler: TransformHandler,
+    private view: WebGLGameView,
+  ) {}
+
+  init() {
+    this.eventBus.on(MouseMoveEvent, (e) => this.onMouseMove(e));
+  }
+
+  private onMouseMove(e: MouseMoveEvent): void {
+    const cell = this.transformHandler.screenToWorldCoordinates(e.x, e.y);
+    let ownerID = 0;
+    if (this.game.isValidCoord(cell.x, cell.y)) {
+      const ref = this.game.ref(cell.x, cell.y);
+      ownerID = this.game.tileState(ref) & OWNER_MASK;
+    }
+    if (ownerID === this.lastOwnerID) return;
+    this.lastOwnerID = ownerID;
+    this.view.setHighlightOwner(ownerID);
+  }
+}