Worker now self-clocks; no heartbeats needed

GameRunner exposes pending work via a new hasPendingTurns() so the worker can check whether more ticks need to be processed.
Worker auto-runs ticks: as soon as it initializes or receives a new turn, it calls processPendingTurns() and loops executeNextTick() while hasPendingTurns() is true. No more "heartbeat" message type; the worker no longer depends on the main thread’s RAF loop to advance the simulation.
Client main thread simplified:
Removed CATCH_UP_HEARTBEATS_PER_FRAME, the heartbeat loop, and the lastBeatsPerFrame tracking.
keepWorkerAlive now just manages frame skipping + draining. When it decides to render (based on renderEveryN), it drains pendingUpdates, merges them, updates GameView, and runs renderer.tick().
Because rendering a batch always implies draining, we restored the invariant that every GameView.update is paired with a layer tick() (no more lost incremental updates).
MAX_RENDER_EVERY_N is now 5 to keep the queue from growing too large while the worker sprints.

src/core/GameRunner.ts

@@ -272,4 +272,8 @@ export class GameRunner {
     }
     return player.bestTransportShipSpawn(targetTile);
   }
+
+  public hasPendingTurns(): boolean {
+    return this.currTurn < this.turns.length;
+  }
 }

src/core/worker/Worker.worker.ts

@@ -16,6 +16,7 @@ import {
 const ctx: Worker = self as any;
 let gameRunner: Promise<GameRunner> | null = null;
 const mapLoader = new FetchGameMapLoader(`/maps`, version);
+let isProcessingTurns = false;
 
 function gameUpdate(gu: GameUpdateViewData | ErrorUpdate) {
   // skip if ErrorUpdate
@@ -32,13 +33,33 @@ function sendMessage(message: WorkerMessage) {
   ctx.postMessage(message);
 }
 
+async function processPendingTurns() {
+  if (isProcessingTurns) {
+    return;
+  }
+  if (!gameRunner) {
+    return;
+  }
+
+  const gr = await gameRunner;
+  if (!gr || !gr.hasPendingTurns()) {
+    return;
+  }
+
+  isProcessingTurns = true;
+  try {
+    while (gr.hasPendingTurns()) {
+      gr.executeNextTick();
+    }
+  } finally {
+    isProcessingTurns = false;
+  }
+}
+
 ctx.addEventListener("message", async (e: MessageEvent<MainThreadMessage>) => {
   const message = e.data;
 
   switch (message.type) {
-    case "heartbeat":
-      (await gameRunner)?.executeNextTick();
-      break;
     case "init":
       try {
         gameRunner = createGameRunner(
@@ -51,6 +72,7 @@ ctx.addEventListener("message", async (e: MessageEvent<MainThreadMessage>) => {
             type: "initialized",
             id: message.id,
           } as InitializedMessage);
+          processPendingTurns();
           return gr;
         });
       } catch (error) {
@@ -67,6 +89,7 @@ ctx.addEventListener("message", async (e: MessageEvent<MainThreadMessage>) => {
       try {
         const gr = await gameRunner;
         await gr.addTurn(message.turn);
+        processPendingTurns();
       } catch (error) {
         console.error("Failed to process turn:", error);
         throw error;