v25 meta update (#1872)

## Description:

v25 meta update:

- Trade ship spawn rate is determined by number of ports players has and
total number of tradeships on the map
- Train spawn rate scales hyperbolically with number of factories owned
by player
- Factory & Port share the same early unit discount (eg building a port
makes the factory more expensive), this is to encourage more
specialization: become a naval economy or land based economy.
- Trains spawn from factories and arrive on cities
- Trains only give gold on cities
- Trains give 50k gold for allies, 25k for nonallies, and 10k for self
- Large players are given a 30% speed/attack debuff in sigmoid curve
- Reduced attack bonus for large players
- Nerf bot gold production from 1k/s => 500/s
- Nerf bot max troops

## 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:

evan

tests/core/game/TrainStation.test.ts

@@ -61,9 +61,9 @@ describe("TrainStation", () => {
 
     station.onTrainStop(trainExecution);
 
-    expect(unit.owner().addGold).toHaveBeenCalledWith(2000n, unit.tile());
+    expect(unit.owner().addGold).toHaveBeenCalledWith(1000n, unit.tile());
     expect(trainExecution.owner().addGold).toHaveBeenCalledWith(
-      2000n,
+      1000n,
       unit.tile(),
     );
   });