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/client/hud/NameBoxCalculator.ts

@@ -122,7 +122,6 @@ export function createGrid(
       if (game.isOnMap(cell)) {
         const tile = game.ref(cell.x, cell.y);
         grid[x - scaledBoundingBox.min.x][y - scaledBoundingBox.min.y] =
-          game.isLake(tile) ||
           game.isShore(tile) ||
           (game.isOcean(tile) && game.magnitude(tile) < 10) ||
           game.owner(tile) === player ||