Added a public game modifier system 😮 For more variety (#2801)

## Description:

Added a public game modifier system. It causes that

5% of public games are played on the compact version of the map
10% of public games have "Random Spawn" activated

Percentages can easily get changed via `DefaultConfig`.
We can also easily add more modifiers.
Modifiers can stack, so in rare cases you will play on a compact map
with random spawn 😄
More variety!

### "Compact Map" modifier implementation

- With the "Compact Map" modifier the lobby max player count gets
reduced to 25% and only 25% of the regular bots and only 25% of the
regular nations will spawn (because the map has only 25% of its regular
size)
- In private lobbies and singleplayer the nation reduction happens too
(When "Compact Map" is enabled).

### Restrictions

- Duos/Trios/Quads team modes do not get Random Spawn (defeats the
purpose)
- Maps with smallest player count < 50 do not get Compact Map in team
games (not enough players after the reduction to 25%). I have calculated
all the possible max player counts.

### How it looks like

Random Spawn modifier:

<img width="528" height="183" alt="Screenshot 2026-01-06 194959"
src="https://github.com/user-attachments/assets/2f729da9-80c3-4548-8205-71129da2a76a"
/>

Very rare case: Two modifiers at the same time and only 10 max players
have been chosen from `[GameMapType.FaroeIslands]: [20, 15, 10]`.
Because of the 75% reduction in player count only 3 players are allowed
(3 is the minimum). I think its funny that you can play a 1v1v1 in rare
occasions 😄

<img width="526" height="184" alt="Screenshot 2026-01-06 194938"
src="https://github.com/user-attachments/assets/834326eb-df03-41b7-b1db-1efa3f1013b5"
/>

### Funny side-effect

Team games with random spawn. That will be interesting. No more "Who is
better in donating troops to the frontline". Instead you have to heavily
coordinate with your teammates.

## 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

src/client/HostLobbyModal.ts

@@ -14,6 +14,7 @@ import {
   UnitType,
   mapCategories,
 } from "../core/game/Game";
+import { getCompactMapNationCount } from "../core/game/NationCreation";
 import { UserSettings } from "../core/game/UserSettings";
 import {
   ClientInfo,
@@ -944,6 +945,7 @@ export class HostLobbyModal extends LitElement {
   /**
    * Returns the effective nation count for display purposes.
    * In HumansVsNations mode, this equals the number of human players.
+   * For compact maps, only 25% of nations are used.
    * Otherwise, it uses the manifest nation count (or 0 if nations are disabled).
    */
   private getEffectiveNationCount(): number {
@@ -953,7 +955,7 @@ export class HostLobbyModal extends LitElement {
     if (this.gameMode === GameMode.Team && this.teamCount === HumansVsNations) {
       return this.clients.length;
     }
-    return this.nationCount;
+    return getCompactMapNationCount(this.nationCount, this.compactMap);
   }
 }