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

tests/Attack.test.ts

@@ -333,6 +333,54 @@ describe("Attack race condition with alliance requests", () => {
   });
 });
 
+describe("Transport ship alliance rejection", () => {
+  beforeEach(async () => {
+    game = await setup("ocean_and_land", {
+      infiniteGold: true,
+      instantBuild: true,
+      infiniteTroops: true,
+    });
+
+    const playerAInfo = new PlayerInfo(
+      "playerA",
+      PlayerType.Human,
+      null,
+      "playerA_id",
+    );
+    // close to the water to send boats
+    playerA = addPlayerToGame(playerAInfo, game, game.ref(7, 0));
+
+    const playerBInfo = new PlayerInfo(
+      "playerB",
+      PlayerType.Human,
+      null,
+      "playerB_id",
+    );
+    playerB = addPlayerToGame(playerBInfo, game, game.ref(7, 15));
+
+    while (game.inSpawnPhase()) {
+      game.executeNextTick();
+    }
+  });
+
+  test("Should cancel alliance requests if the recipient sends a transport ship", async () => {
+    // Player A sends alliance request to Player B
+    const allianceRequest = playerA.createAllianceRequest(playerB);
+    expect(allianceRequest).not.toBeNull();
+    expect(playerB.incomingAllianceRequests()).toHaveLength(1);
+
+    // Player B sends a transport ship toward Player A's territory
+    game.addExecution(new TransportShipExecution(playerB, game.ref(7, 0), 0));
+
+    // Execute a tick to process the transport ship launch
+    game.executeNextTick();
+
+    // Alliance request should be rejected since player B sent a naval invasion
+    expect(playerA.outgoingAllianceRequests()).toHaveLength(0);
+    expect(playerB.incomingAllianceRequests()).toHaveLength(0);
+  });
+});
+
 describe("Attack immunity", () => {
   beforeEach(async () => {
     game = await setup("ocean_and_land", {