Fix map land tile lookup broken by asset URL migration 🗺️ (#3826)

## Description:

`MapLandTiles` was fetching map manifests via HTTP at
`http://localhost:3000/maps/<map>/manifest.json`. This stopped working
after PR #3494 moved all public assets from stable paths (e.g.
`/maps/...`) to content-hashed paths under `/_assets/...`. The master
server no longer serves `/maps/` -- requests fell through to the SPA
handler, returned `index.html`, failed JSON parsing, and silently fell
back to the default `1_000_000` land tile count.

With 1M tiles, `calculateMapPlayerCounts` produces `[50, 40, 25]`
instead of the real values (e.g. `[185, 140, 95]` for Alps), causing all
public lobbies to be capped at 25-50 players regardless of map.

Fixes this by reading map manifests directly from disk instead of via
HTTP:
- In production: resolves the source path through
`getRuntimeAssetManifest()` to the hashed file under `static/_assets/`,
then reads it with `fs.readFile`.
- In dev: falls back to `resources/maps/<name>/manifest.json` directly
(the Dockerfile removes `resources/maps` in production, so this branch
only runs locally).

Also adds an in-process cache so each map manifest is only read once per
server lifetime.

Verified that it works on
https://fix-map-land-tiles-asset-manifest.openfront.dev/ and locally.

## 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/server/MapLandTiles.ts

@@ -1,26 +1,57 @@
-import { FetchGameMapLoader } from "src/core/game/FetchGameMapLoader";
+import fs from "fs/promises";
+import path from "path";
+import { normalizeAssetPath } from "src/core/AssetUrls";
 import { GameMapType } from "src/core/game/Game";
-import { GameMapLoader } from "src/core/game/GameMapLoader";
+import { fileURLToPath } from "url";
 import { logger } from "./Logger";
-
-let mapLoader: GameMapLoader | null = null;
+import { getRuntimeAssetManifest } from "./RuntimeAssetManifest";
 
 const log = logger.child({ component: "MapLandTiles" });
 
-// Gets or creates the map loader, uses FetchGameMapLoader pointing to the master server.
-function getMapLoader(): GameMapLoader {
-  mapLoader ??= new FetchGameMapLoader("http://localhost:3000/maps");
-  return mapLoader;
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const staticDir = path.join(__dirname, "../../static");
+const resourcesDir = path.join(__dirname, "../../resources");
+
+const landTilesCache = new Map<GameMapType, number>();
+
+function mapDirName(map: GameMapType): string {
+  const key = (
+    Object.keys(GameMapType) as Array<keyof typeof GameMapType>
+  ).find((k) => GameMapType[k] === map);
+  if (!key) throw new Error(`Unknown map: ${map}`);
+  return key.toLowerCase();
 }
 
-// Gets the number of land tiles for a map
-// FetchGameMapLoader already caches maps, so no need for additional caching here.
+async function readManifestFile(map: GameMapType): Promise<string> {
+  const relativePath = `maps/${mapDirName(map)}/manifest.json`;
+
+  // Production: resolve via the asset manifest to the hashed file under static/_assets/.
+  const assetManifest = await getRuntimeAssetManifest();
+  const hashedUrl = assetManifest[relativePath];
+  if (hashedUrl) {
+    return fs.readFile(
+      path.join(staticDir, normalizeAssetPath(hashedUrl)),
+      "utf8",
+    );
+  }
+
+  // Dev: read directly from resources/. The Dockerfile deletes resources/maps in
+  // production, so this branch only runs locally.
+  return fs.readFile(path.join(resourcesDir, relativePath), "utf8");
+}
+
+// Gets the number of land tiles for a map.
 export async function getMapLandTiles(map: GameMapType): Promise<number> {
+  const cached = landTilesCache.get(map);
+  if (cached !== undefined) return cached;
+
   try {
-    const loader = getMapLoader();
-    const mapData = loader.getMapData(map);
-    const manifest = await mapData.manifest();
-    return manifest.map.num_land_tiles;
+    const raw = await readManifestFile(map);
+    const tiles = (JSON.parse(raw) as { map: { num_land_tiles: number } }).map
+      .num_land_tiles;
+    landTilesCache.set(map, tiles);
+    return tiles;
   } catch (error) {
     log.error(`Failed to load manifest for ${map}: ${error}`, { map });
     return 1_000_000; // Default fallback