refactor: collapse per-env Configs into ClientEnv + ServerEnv (#3906)

## Description:

This is a refactor to simplify config handling.

Replaces the per-environment DevConfig/PreprodConfig/ProdConfig class
hierarchy with two static classes: ClientEnv (browser main thread, reads
from window.BOOTSTRAP_CONFIG) and ServerEnv (Node server, reads from
process.env). The four config classes are deleted, the abstract
DefaultServerConfig is gone, and DefaultConfig is renamed to Config.

The values that flow server → client (gameEnv, numWorkers,
turnstileSiteKey, jwtAudience, instanceId) used to be baked into the
hardcoded per-env classes. They're now real env vars on the server,
embedded into a single window.BOOTSTRAP_CONFIG object in index.html at
request time (alongside the existing gitCommit/assetManifest/cdnBase
globals, which moved into the same object), and read back by ClientEnv
on the client. The dev defaults previously hidden inside DevServerConfig
are now explicit in start:server-dev (NUM_WORKERS=2,
TURNSTILE_SITE_KEY=1x..., JWT_AUDIENCE=localhost, etc.) and in
vite.config.ts's html plugin inject.data. Production deploys plumb
NUM_WORKERS and TURNSTILE_SITE_KEY through deploy.yml (GitHub vars) into
the remote env file; JWT_AUDIENCE is derived from DOMAIN in deploy.sh.
The dynamic /api/instance endpoint is gone — INSTANCE_ID rides along in
BOOTSTRAP_CONFIG now.

ServerEnv is the only thing server code touches; ClientEnv is
browser-only. The two classes have intentional overlap (env, numWorkers,
jwtIssuer, gameCreationRate, workerIndex, etc.) since they derive
identical logic from different sources — there's a TODO in each to
consolidate via a shared helper later. The game-logic Config no longer
stores a ServerConfig/ClientEnv reference and its serverConfig() getter
is gone; the one caller (MultiTabModal) now reads ClientEnv.env()
directly. Worker init no longer carries server-config values since
nothing in the worker actually reads them.

## 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

src/server/Master.ts

@@ -6,15 +6,14 @@ import http from "http";
 import path from "path";
 import { fileURLToPath } from "url";
 import { GameEnv } from "../core/configuration/Config";
-import { getServerConfigFromServer } from "../core/configuration/ConfigLoader";
 import { logger } from "./Logger";
 import { MapPlaylist } from "./MapPlaylist";
 import { MasterLobbyService } from "./MasterLobbyService";
 import { setNoStoreHeaders } from "./NoStoreHeaders";
 import { renderAppShell } from "./RenderHtml";
+import { ServerEnv } from "./ServerEnv";
 import { applyStaticAssetCacheControl } from "./StaticAssetCache";
 
-const config = getServerConfigFromServer();
 const playlist = new MapPlaylist();
 let lobbyService: MasterLobbyService;
 
@@ -79,16 +78,16 @@ export async function startMaster() {
   }
 
   log.info(`Primary ${process.pid} is running`);
-  log.info(`Setting up ${config.numWorkers()} workers...`);
+  log.info(`Setting up ${ServerEnv.numWorkers()} workers...`);
 
-  lobbyService = new MasterLobbyService(config, playlist, log);
+  lobbyService = new MasterLobbyService(playlist, log);
 
   // Generate admin token for worker authentication
   const ADMIN_TOKEN = crypto.randomBytes(16).toString("hex");
   process.env.ADMIN_TOKEN = ADMIN_TOKEN;
 
   const INSTANCE_ID =
-    config.env() === GameEnv.Dev
+    ServerEnv.env() === GameEnv.Dev
       ? "DEV_ID"
       : crypto.randomBytes(4).toString("hex");
   process.env.INSTANCE_ID = INSTANCE_ID;
@@ -96,7 +95,7 @@ export async function startMaster() {
   log.info(`Instance ID: ${INSTANCE_ID}`);
 
   // Fork workers
-  for (let i = 0; i < config.numWorkers(); i++) {
+  for (let i = 0; i < ServerEnv.numWorkers(); i++) {
     const worker = cluster.fork({
       WORKER_ID: i,
       ADMIN_TOKEN,
@@ -151,12 +150,6 @@ app.get("/api/health", (_req, res) => {
   }
 });
 
-app.get("/api/instance", (_req, res) => {
-  res.json({
-    instanceId: process.env.INSTANCE_ID ?? "undefined",
-  });
-});
-
 // SPA fallback route
 app.get("/{*splat}", async function (_req, res) {
   try {