feat: F5.6b server F as an image: the editor from F itself, one stack per environment

F hands out the editor's page and bundle (editor/ beside main.mjs, or
FILIUS_EDITOR_DIR): GET and HEAD only, one wall against leaving the folder,
F's own routes first, assets/ cached a year, the rest asked for again; the
build lays .br and .gz beside the files and F sends the better one the
browser takes (bundle 695 KB to 212 KB).

deploy/Dockerfile: two stages, Node 24, no node_modules, not root.
deploy/docker-compose.yml with an env file per environment: the file sets
the stack's name, volume, image tag and port (test 8081, production 8080).
Measured with both stacks side by side behind nginx and Chromium.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/server/src/server.ts

@@ -3,8 +3,9 @@
 // the dashboard (with the service key), /blobs for the large binary files
 // of the projects' computers, the WebSockets /sync for the shared
 // documents and /sim?project=… for the simulation rooms (the session's grant
-// decides there as at /sync; a refusal closes the socket with its reason);
-// anything else is not found. A WebSocket from a page of another
+// decides there as at /sync; a refusal closes the socket with its reason),
+// and the editor's page and bundle (editorFiles.ts) for anything else; what
+// is none of these is not found. A WebSocket from a page of another
 // origin is refused (a page elsewhere under the same domain would bring the
 // person's cookie along: SameSite only tells sites apart). Closed, it first
 // takes no one new (a client lets go and comes back at once, which would
@@ -21,6 +22,7 @@ import { WebSocketServer, type WebSocket } from 'ws';
 import { exchangeTicket } from './auth.js';
 import { handleBlobs } from './blobRoutes.js';
 import type { BlobStore } from './blobs.js';
+import type { EditorFiles } from './editorFiles.js';
 import { errorText, type Log } from './log.js';
 import { handleService } from './service.js';
 import { holdMessages, SimRooms } from './simRooms.js';
@@ -50,6 +52,8 @@ export interface ServerOptions extends SyncOptions {
   /** The bundled room thread (dist/simWorker.mjs). */
   readonly workerUrl: URL;
   readonly blobs: BlobStore;
+  /** The editor's page and bundle; without them only F's own routes answer (development, tests). */
+  readonly editor?: EditorFiles;
   readonly simThreads?: number;
   readonly lingerMilliseconds?: number;
   readonly pingMilliseconds?: number;
@@ -111,7 +115,7 @@ export async function startServer(options: ServerOptions): Promise<FiliusServer>
     else if (request.method === 'GET' && path === '/__auth') await exchangeTicket(request, response, options);
     else if (path.startsWith('/svc/')) await handleService(request, response, path, { ...options, sync, sims });
     else if (path === '/blobs' || path.startsWith('/blobs/')) await handleBlobs(request, response, new URL(request.url ?? '/', 'http://filius'), options);
-    else json(response, 404, { error: 'notFound' });
+    else if (options.editor === undefined || !(await options.editor(request, response, path))) json(response, 404, { error: 'notFound' });
   };
   const http: Server = createServer((request, response) => {
     const path = new URL(request.url ?? '/', 'http://filius').pathname;