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/Archive.ts

@@ -1,5 +1,4 @@
 import z from "zod";
-import { getServerConfigFromServer } from "../core/configuration/ConfigLoader";
 import { GameType } from "../core/game/Game";
 import {
   GameID,
@@ -10,8 +9,7 @@ import {
 } from "../core/Schemas";
 import { replacer } from "../core/Util";
 import { logger } from "./Logger";
-
-const config = getServerConfigFromServer();
+import { ServerEnv } from "./ServerEnv";
 
 const log = logger.child({ component: "Archive" });
 
@@ -31,13 +29,13 @@ export async function archive(
       });
       return;
     }
-    const url = `${config.jwtIssuer()}/game/${gameRecord.info.gameID}`;
+    const url = `${ServerEnv.jwtIssuer()}/game/${gameRecord.info.gameID}`;
     const response = await fetch(url, {
       method: "POST",
       body: JSON.stringify(gameRecord, replacer),
       headers: {
         "Content-Type": "application/json",
-        "x-api-key": config.apiKey(),
+        "x-api-key": ServerEnv.apiKey(),
       },
     });
     if (!response.ok) {
@@ -62,12 +60,12 @@ export async function readGameRecord(
       log.error(`invalid game ID: ${gameId}`);
       return null;
     }
-    const url = `${config.jwtIssuer()}/game/${gameId}`;
+    const url = `${ServerEnv.jwtIssuer()}/game/${gameId}`;
     const response = await fetch(url, {
       method: "GET",
       headers: {
         "Content-Type": "application/json",
-        "x-api-key": config.apiKey(),
+        "x-api-key": ServerEnv.apiKey(),
       },
     });
     const record = await response.json();
@@ -91,9 +89,9 @@ export function finalizeGameRecord(
 ): GameRecord {
   return {
     ...clientRecord,
-    gitCommit: config.gitCommit(),
-    subdomain: config.subdomain(),
-    domain: config.domain(),
+    gitCommit: ServerEnv.gitCommit(),
+    subdomain: ServerEnv.subdomain(),
+    domain: ServerEnv.domain(),
   };
 }