Auto-reject alliance request when transport ship is sent to target player (#3477)

## Description:

When a player sends a transport ship toward another player's territory,
any pending alliance request from the target is now automatically
rejected.
This mirrors the behavior already in place for direct attacks,
preventing a player from exploiting a pending alliance request while
launching a naval invasion.

## 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:

deshack_82603

src/core/execution/TransportShipExecution.ts

@@ -4,6 +4,7 @@ import {
   Game,
   MessageType,
   Player,
+  PlayerType,
   TerraNullius,
   Unit,
   UnitType,
@@ -76,6 +77,16 @@ export class TransportShipExecution implements Execution {
       return;
     }
 
+    if (this.target.isPlayer()) {
+      const targetPlayer = this.target as Player;
+      if (
+        targetPlayer.type() !== PlayerType.Bot &&
+        this.attacker.type() !== PlayerType.Bot
+      ) {
+        this.rejectIncomingAllianceRequests(targetPlayer);
+      }
+    }
+
     if (this.target.isPlayer() && !this.attacker.canAttackPlayer(this.target)) {
       this.active = false;
       return;
@@ -290,4 +301,13 @@ export class TransportShipExecution implements Execution {
   isActive(): boolean {
     return this.active;
   }
+
+  private rejectIncomingAllianceRequests(target: Player) {
+    const request = this.attacker
+      .incomingAllianceRequests()
+      .find((ar) => ar.requestor() === target);
+    if (request !== undefined) {
+      request.reject();
+    }
+  }
 }