make spawn glow follow the player's currently selected spawn tile

Plumb spawnTile through PlayerUpdate / PlayerState / applyStateUpdate
so the WebGL spawn overlay can read it directly. The glow was reading
nameData.x/y (territory centroid for label placement) which only
recomputes every 2 ticks and only when largestClusterBoundingBox has
been updated by PlayerExecution — both lag the player's actual spawn
click. Using spawnTile updates the same tick setSpawnTile() fires.

Also adds spawnTile to diffPlayerUpdate / applyStateUpdate so changes
after the initial full snapshot actually propagate (the recent
diff-only PlayerUpdate path silently dropped any field not enumerated
in those helpers).

src/client/WebGLFrameBuilder.ts

@@ -91,7 +91,8 @@ export class WebGLFrameBuilder {
     const centers: SpawnCenter[] = [];
     for (const p of gameView.players()) {
       if (!p.isPlayer() || p.type() !== PlayerType.Human) continue;
-      if (!p.hasSpawned()) continue;
+      const spawnTile = p.state.spawnTile;
+      if (spawnTile === undefined) continue;
       const isSelf = me !== null && p.smallID() === me.smallID();
       // myPlayer reads as plain white so the local-player ring is visually
       // distinct from any team color; everyone else uses their territory tint.
@@ -99,8 +100,11 @@ export class WebGLFrameBuilder {
         ? { r: 255, g: 255, b: 255 }
         : p.territoryColor().toRgb();
       centers.push({
-        x: p.nameData?.x ?? 0,
-        y: p.nameData?.y ?? 0,
+        // spawnTile tracks the player's currently-selected spawn directly —
+        // updates the same tick the player picks a new location (faster than
+        // the nameData centroid which only refreshes every 2 ticks).
+        x: gameView.x(spawnTile),
+        y: gameView.y(spawnTile),
         r: c.r / 255,
         g: c.g / 255,
         b: c.b / 255,

src/client/render/types/Renderer.ts

@@ -61,6 +61,8 @@ export interface PlayerState {
   traitorRemainingTicks: number;
   betrayals: number;
   hasSpawned: boolean;
+  /** TileRef the player picked as their spawn (undefined if not yet spawned). */
+  spawnTile?: number;
   lastDeleteUnitTick: number;
   allies: number[];
   embargoes: number[];

src/client/view/PlayerView.ts

@@ -82,6 +82,7 @@ function stateFromUpdate(pu: PlayerUpdate): PlayerState {
     traitorRemainingTicks: Math.max(0, pu.traitorRemainingTicks ?? 0),
     betrayals: pu.betrayals!,
     hasSpawned: pu.hasSpawned!,
+    spawnTile: pu.spawnTile,
     lastDeleteUnitTick: pu.lastDeleteUnitTick!,
     allies: pu.allies!.slice(),
     embargoes: [],

src/core/game/GameUpdateUtils.ts

@@ -43,6 +43,7 @@ export function diffPlayerUpdate(
     prev.traitorRemainingTicks === next.traitorRemainingTicks,
   );
   setIfDifferent("hasSpawned", prev.hasSpawned === next.hasSpawned);
+  setIfDifferent("spawnTile", prev.spawnTile === next.spawnTile);
   setIfDifferent("betrayals", prev.betrayals === next.betrayals);
   setIfDifferent(
     "lastDeleteUnitTick",
@@ -97,6 +98,7 @@ export function applyStateUpdate(target: PlayerState, pu: PlayerUpdate): void {
   }
   if (pu.betrayals !== undefined) target.betrayals = pu.betrayals;
   if (pu.hasSpawned !== undefined) target.hasSpawned = pu.hasSpawned;
+  if (pu.spawnTile !== undefined) target.spawnTile = pu.spawnTile;
   if (pu.lastDeleteUnitTick !== undefined) {
     target.lastDeleteUnitTick = pu.lastDeleteUnitTick;
   }

src/core/game/GameUpdates.ts

@@ -198,6 +198,7 @@ export interface PlayerUpdate {
   outgoingAllianceRequests?: PlayerID[];
   alliances?: AllianceView[];
   hasSpawned?: boolean;
+  spawnTile?: TileRef;
   betrayals?: number;
   lastDeleteUnitTick?: Tick;
   isLobbyCreator?: boolean;

src/core/game/PlayerImpl.ts

@@ -202,6 +202,7 @@ export class PlayerImpl implements Player {
           }) satisfies AllianceView,
       ),
       hasSpawned: this.hasSpawned(),
+      spawnTile: this._spawnTile,
       betrayals: this._betrayalCount,
       lastDeleteUnitTick: this.lastDeleteUnitTick,
       isLobbyCreator: this.isLobbyCreator(),