Import december-2020-12-18 from private repo (scrubbed 2026-05-27)

Targets Rec Room 2020.12.18 client.

Re-import after adding:
- DorkNet.ClientMod/dorknet-clientmod.json.template — config schema
  the launcher's manifest-driven patcher renders into UserData/.
- tools/build-patcher-zip.ps1 — produces the dorknet-clientpatch-{key}.zip
  Release asset the launcher fetches.
- .github/workflows/release.yml — auto-publishes both Release assets
  on v1-december-* tag push.

Scrubbed via maintainer-side scrub-for-public.ps1: same drop rules as
the prior import, plus build-patcher-zip.ps1 added to the tools/
allow-list so it survives the scrub.

DorkNet.Server/admin-ui/src/pages/Broadcast.tsx

@@ -0,0 +1,56 @@
+import { useState } from 'react';
+import { api } from '../lib/api';
+import { PageHeader } from '../components/PageHeader';
+import { useToast } from '../components/Toast';
+
+export function Broadcast() {
+  const [message, setMessage] = useState('');
+  const [busy, setBusy] = useState(false);
+  const toast = useToast();
+
+  const send = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!message.trim()) return;
+    if (!confirm(`Broadcast this to every connected player?\n\n"${message}"`)) return;
+    setBusy(true);
+    try {
+      await api('/broadcast', { method: 'POST', body: { Message: message } });
+      toast.push('Broadcast sent', 'success');
+      setMessage('');
+    } catch (e) {
+      toast.push((e as Error).message, 'error');
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <div>
+      <PageHeader
+        title="Broadcast"
+        blurb="Push a server-maintenance notification to every connected player. The watch shows it as a system toast."
+      />
+
+      <form onSubmit={send} className="card !p-5 max-w-2xl">
+        <label className="label">Message</label>
+        <textarea
+          value={message}
+          onChange={e => setMessage(e.target.value)}
+          rows={5}
+          className="input mt-1.5 font-mono text-sm"
+          placeholder="Server going down for maintenance in 5 minutes — log out cleanly to avoid losing your dorm save."
+          required
+        />
+        <div className="mt-2 text-xs text-ink-400">
+          {message.length} characters
+        </div>
+        <div className="mt-4 flex gap-2 justify-end">
+          <button type="button" onClick={() => setMessage('')} className="btn-ghost text-xs" disabled={busy || !message}>Clear</button>
+          <button className="btn-primary text-xs" disabled={busy || !message.trim()}>
+            {busy ? 'Sending…' : 'Send broadcast'}
+          </button>
+        </div>
+      </form>
+    </div>
+  );
+}