Remove lakes from the game 🌊 (#4214)

## Description:

Nametags look weird here because on the left is a lake:

<img width="954" height="765" alt="Screenshot 2026-06-10 170116"
src="https://github.com/user-attachments/assets/2b679a68-fab3-458e-8e29-e12b9a4f281b"
/>

I removed isLake from the nametag position calculation

Because isLake was unused then, I removed it completely.

Full changelog:

- Remove isLake() from GameMap interface, GameMapImpl, GameImpl, and
GameView
- Remove TerrainType.Lake enum value
- terrainType() now returns Ocean for all water tiles (previously
distinguished lake vs ocean, but nothing treated them differently)
- Remove Lake case from PastelTheme and PastelThemeDark (already fell
through to Ocean)
- Exclude lakes from nametag placement grid in NameBoxCalculator

Maybe as a next step also remove lakes metadata from the map generator?

AI Model used: MiMo 2.5 Pro

## 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

## Please put your Discord username so you can be contacted if a bug or
regression is found:

FloPinguin

src/core/game/Game.ts

@@ -523,7 +523,6 @@ export enum TerrainType {
   Plains,
   Highland,
   Mountain,
-  Lake,
   Ocean,
 }
 

src/core/game/GameImpl.ts

@@ -1149,9 +1149,6 @@ export class GameImpl implements Game {
   isWater(ref: TileRef): boolean {
     return this._map.isWater(ref);
   }
-  isLake(ref: TileRef): boolean {
-    return this._map.isLake(ref);
-  }
   isShore(ref: TileRef): boolean {
     return this._map.isShore(ref);
   }

src/core/game/GameMap.ts

@@ -37,7 +37,6 @@ export interface GameMap {
   isBorder(ref: TileRef): boolean;
   neighbors(ref: TileRef): TileRef[];
   isWater(ref: TileRef): boolean;
-  isLake(ref: TileRef): boolean;
   isShore(ref: TileRef): boolean;
   cost(ref: TileRef): number;
   terrainType(ref: TileRef): TerrainType;
@@ -311,10 +310,6 @@ export class GameMapImpl implements GameMap {
     return !this.isLand(ref);
   }
 
-  isLake(ref: TileRef): boolean {
-    return !this.isLand(ref) && !this.isOcean(ref);
-  }
-
   isShore(ref: TileRef): boolean {
     return this.isLand(ref) && this.isShoreline(ref);
   }
@@ -332,7 +327,7 @@ export class GameMapImpl implements GameMap {
       if (magnitude < 20) return TerrainType.Highland;
       return TerrainType.Mountain;
     }
-    return this.isOcean(ref) ? TerrainType.Ocean : TerrainType.Lake;
+    return TerrainType.Ocean;
   }
 
   neighbors(ref: TileRef): TileRef[] {