Add PVP immunity to 5M starting gold modifier games 🔧 (#3180)

## Description:

Adds 30 seconds of PVP immunity to 5M starting gold modifier games.
So you cannot insta-nuke other players.

Because I'm sure people would be confused "I cannot attack!!!!" I added
a HeadsUpMessage which informs about the PVP immunity.
We already have a ImmunityTimer progress bar but I don't think its
enough.

<img width="1270" height="745" alt="image"
src="https://github.com/user-attachments/assets/0ee23dc4-1c7b-4d62-8b3d-8de214f03c2b"
/>

I had a second count in the HeadsUpMessage (seconds until PVP immunity
is over) but it felt too busy. So I removed it. You can tell when PVP
immunity is over by looking at the progress bar.

## 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:

FloPinguin

---------

Co-authored-by: Evan <evanpelle@gmail.com>

tests/Attack.test.ts

@@ -391,17 +391,17 @@ describe("Attack immunity", () => {
 
   test("Ensure a player can't attack during all the immunity phase", async () => {
     // Execute a few ticks but stop right before the immunity phase is over
-    for (let i = 0; i < immunityPhaseTicks - 1; i++) {
+    for (let i = 0; i < immunityPhaseTicks - 2; i++) {
       game.executeNextTick();
     }
     // Player A attacks Player B
     game.addExecution(new AttackExecution(null, playerA, playerB.id(), null));
-    game.executeNextTick(); // ticks === immunityPhaseTicks here
+    game.executeNextTick(); // ticks === immunityPhaseTicks - 1 here
     // Attack is not possible during immunity
     expect(playerA.outgoingAttacks()).toHaveLength(0);
 
     // Retry after the immunity is over
-    game.executeNextTick(); // ticks === immunityPhaseTicks + 1
+    game.executeNextTick(); // ticks === immunityPhaseTicks
     game.addExecution(new AttackExecution(null, playerA, playerB.id(), null));
     game.executeNextTick();
     // Attack is now possible right after