rename Layer → Controller; drop canvas2D-era interface hooks

The Layer interface dates to the canvas2D era when each entry drew to
the shared 2D context via renderLayer(ctx). With canvas2D gone, nothing
draws there and the renderLayer hook is dead. Rename the interface
("main-thread analog of the worker's Execution") and trim it:

  interface Controller {
    init?: () => void;
    tick?: () => void;
    getTickIntervalMs?: () => number;
  }

renderLayer / shouldTransform / redraw are gone.

Sweep across 28 files: from "./Layer" → "./Controller", implements
Layer → implements Controller, Layer[] / Map<Layer,…> →
Controller[] / Map<Controller,…>. Delete the no-op renderLayer +
shouldTransform method bodies that every layer had inherited.

GameRenderer drops the RedrawGraphicsEvent listener + redraw() fanout
(nothing implements redraw anymore) and the now-unused eventBus
constructor field.

One real case: AttackingTroopsOverlay.renderLayer wasn't a no-op — it
updates DOM label transforms each frame so labels track the WebGL
camera during pan/zoom. Rename to private updateLabelDOM() and start
a self-driven RAF in init() so the per-frame updates keep running.

Class names ending in "Layer" (UILayer, StructureIconsLayer, NameLayer,
etc.) intentionally left as-is — those are separate identifiers and
the class-rename / file-move is a follow-up.

407 tests pass.

src/client/graphics/layers/MultiTabModal.ts

@@ -6,10 +6,10 @@ import { GameType } from "../../../core/game/Game";
 import { GameView } from "../../../core/game/GameView";
 import { MultiTabDetector } from "../../MultiTabDetector";
 import { translateText } from "../../Utils";
-import { Layer } from "./Layer";
+import { Controller } from "./Controller";
 
 @customElement("multi-tab-modal")
-export class MultiTabModal extends LitElement implements Layer {
+export class MultiTabModal extends LitElement implements Controller {
   public game: GameView;
 
   private detector: MultiTabDetector;