fix: allies cannot annex your clusters (#2158)

## Description:

Fixes #1685
Continuation from #1924, which was auto-closed after the upstream repo
force-pushed main and I synced my fork.

This change ensures that allies are excluded from the `getMode()` call
made by `getCapturingPlayer()` inside `removeCluster()`.

- Previously, friendly neighbors were treated as candidates for
capturing, leading to incorrect annexations in certain edge cases.
- Added a small efficiency improvement by filtering out non-player and
friendly neighbors up front to reduce total computations down-the-line.
- Important: we can’t simply check if the `getMode(neighborsIDs)` result
is a friendly. Doing so would cause the territory to go to nobody until
the user is attacked. I believe the expected behavior is the largest
neighboring enemy should take it automatically.

Here's an example of the new behavior in an extreme edge case:
<img width="622" height="422" alt="Screenshot 2025-08-24 at 4 56 46 PM"
src="https://github.com/user-attachments/assets/c5dd9c0d-0a3c-4657-8154-e114fa920689"
/>

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

nottirb

src/core/Util.ts

@@ -114,27 +114,6 @@ export function inscribed(
   );
 }
 
-export function getMode(list: Set<number>): number {
-  // Count occurrences
-  const counts = new Map<number, number>();
-  for (const item of list) {
-    counts.set(item, (counts.get(item) ?? 0) + 1);
-  }
-
-  // Find the item with the highest count
-  let mode = 0;
-  let maxCount = 0;
-
-  for (const [item, count] of counts) {
-    if (count > maxCount) {
-      maxCount = count;
-      mode = item;
-    }
-  }
-
-  return mode;
-}
-
 export function sanitize(name: string): string {
   return Array.from(name)
     .join("")

src/core/execution/PlayerExecution.ts

@@ -2,7 +2,7 @@ import { Config } from "../configuration/Config";
 import { Execution, Game, Player, UnitType } from "../game/Game";
 import { GameImpl } from "../game/GameImpl";
 import { GameMap, TileRef } from "../game/GameMap";
-import { calculateBoundingBox, getMode, inscribed, simpleHash } from "../Util";
+import { calculateBoundingBox, inscribed, simpleHash } from "../Util";
 
 export class PlayerExecution implements Execution {
   private readonly ticksPerClusterCalc = 20;
@@ -214,22 +214,37 @@ export class PlayerExecution implements Execution {
   }
 
   private getCapturingPlayer(cluster: Set<TileRef>): Player | null {
-    const neighborsIDs = new Set<number>();
+    // Collect unique neighbor IDs (excluding self) as candidates
+    const candidatesIDs = new Set<number>();
+    const selfID = this.player.smallID();
+
     for (const t of cluster) {
       for (const neighbor of this.mg.neighbors(t)) {
-        if (this.mg.ownerID(neighbor) !== this.player.smallID()) {
-          neighborsIDs.add(this.mg.ownerID(neighbor));
+        if (this.mg.ownerID(neighbor) !== selfID) {
+          candidatesIDs.add(this.mg.ownerID(neighbor));
         }
       }
     }
 
-    let largestNeighborAttack: Player | null = null;
-    let largestTroopCount: number = 0;
-    for (const id of neighborsIDs) {
+    // Filter out friendly and non-player candidates
+    const neighbors = new Set<Player>();
+    for (const id of candidatesIDs) {
       const neighbor = this.mg.playerBySmallID(id);
-      if (!neighbor.isPlayer() || this.player.isFriendly(neighbor)) {
+      if (!neighbor.isPlayer() || neighbor.isFriendly(this.player)) {
         continue;
       }
+      neighbors.add(neighbor);
+    }
+
+    // If there are no enemies, return null
+    if (neighbors.size === 0) {
+      return null;
+    }
+
+    // Get the largest attack from the neighbors
+    let largestNeighborAttack: Player | null = null;
+    let largestTroopCount = 0;
+    for (const neighbor of neighbors) {
       for (const attack of neighbor.outgoingAttacks()) {
         if (attack.target() === this.player) {
           if (attack.troops() > largestTroopCount) {
@@ -239,20 +254,10 @@ export class PlayerExecution implements Execution {
         }
       }
     }
-    if (largestNeighborAttack !== null) {
-      return largestNeighborAttack;
-    }
 
-    // fall back to getting mode if no attacks
-    const mode = getMode(neighborsIDs);
-    if (!this.mg.playerBySmallID(mode).isPlayer()) {
-      return null;
-    }
-    const capturing = this.mg.playerBySmallID(mode);
-    if (!capturing.isPlayer()) {
-      return null;
-    }
-    return capturing;
+    // Return the largest neighbor attack
+    // If there is no largest neighbor attack, this will return null
+    return largestNeighborAttack;
   }
 
   private calculateClusters(): Set<TileRef>[] {