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("")