Allow railroad loops (#1274)

## Description:

This change enables loop formation in the station network, allowing for
enhanced connectivity. However, it can sometimes result in clustered
areas as a trade-off. To mitigate excessive clustering, loops are only
permitted when there are at least 5 intermediary stations between the
source and destination stations.


![image](https://github.com/user-attachments/assets/720fa4f9-a634-49e8-8027-fe4e244d5ae5)

Also a few fixes for `.dev` players.

## 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
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

src/core/configuration/DefaultConfig.ts

@@ -302,7 +302,7 @@ export class DefaultConfig implements Config {
     return Math.min(50, Math.round(10 * Math.pow(numberOfPorts, 0.6)));
   }
   trainSpawnRate(numberOfStations: number): number {
-    return Math.round(50 * Math.pow(numberOfStations, 0.8));
+    return Math.min(1400, Math.round(60 * Math.pow(numberOfStations, 0.8)));
   }
   trainGold(): Gold {
     return BigInt(10_000);
@@ -363,6 +363,7 @@ export class DefaultConfig implements Config {
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
           upgradable: true,
+          canBuildTrainStation: true,
         };
       case UnitType.AtomBomb:
         return {
@@ -452,6 +453,7 @@ export class DefaultConfig implements Config {
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
           upgradable: true,
+          canBuildTrainStation: true,
         };
       case UnitType.Factory:
         return {
@@ -466,6 +468,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
+          canBuildTrainStation: true,
         };
       case UnitType.Construction:
         return {