feat: F5.3a the simulation rooms on server F

One room per project for everyone in it, held by a few worker_threads,
each room with a replica of the document that Hocuspocus' direct
connection keeps open: changes go in, what the room writes comes back.
/sim?project=... signs in as /sync does and says refusals and partings
as the socket's closing; only a write grant changes the room. The state
names who started the simulation. After the last person the room stays
60 s, then stops, writes back and ends. Freezing stops a running
simulation and refuses to start one, deleting ends the room without
writing back, revoking lets the person go from the room too; a failed
thread ends its rooms, stopping the service stops them all.

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

packages/server/package.json

@@ -8,7 +8,7 @@
     ".": "./src/index.ts"
   },
   "scripts": {
-    "build": "esbuild src/main.ts --bundle --platform=node --format=esm --target=node20 --outfile=dist/main.mjs --external:pg-native --banner:js=\"import { createRequire } from 'node:module'; const require = createRequire(import.meta.url);\"",
+    "build": "esbuild src/main.ts src/simWorker.ts --bundle --platform=node --format=esm --target=node20 --outdir=dist --out-extension:.js=.mjs --external:pg-native --banner:js=\"import { createRequire } from 'node:module'; const require = createRequire(import.meta.url);\"",
     "start": "node dist/main.mjs"
   },
   "dependencies": {