Add lobbies: DM sees all characters, players only a short card of others

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HJhXuLD2Z6hv3Wqeq9UL9K

frontend/src/App.jsx

@@ -3,6 +3,7 @@ import Creator from './Creator.jsx'
 import Rules from './Rules.jsx'
 import Characters from './Characters.jsx'
 import Presets from './Presets.jsx'
+import Lobbies from './Lobbies.jsx'
 import Login from './Login.jsx'
 import Account from './Account.jsx'
 import { claimLegacy } from './legacy.js'
@@ -52,7 +53,7 @@ export default function App() {
   if (!auth.user) return <main><Login registrationOpen={auth.registration_open} onDone={(u) => setAuth({ ...auth, user: u })} /></main>
 
   const page = hash.split('/')[0]
-  const nav = [['creator', charName ? `Character: ${charName}` : 'Character'], ['rules', 'Rules'], ['presets', 'Presets'], ['characters', 'My characters']]
+  const nav = [['creator', charName ? `Character: ${charName}` : 'Character'], ['rules', 'Rules'], ['presets', 'Presets'], ['characters', 'My characters'], ['lobbies', 'Lobbies']]
 
   return (
     <>
@@ -77,6 +78,9 @@ export default function App() {
           <Characters onOpen={(entry) => { setLoadRequest(entry); window.location.hash = 'creator' }}
             onNew={() => { setLoadRequest({ new: true }); window.location.hash = 'creator' }} />
         )}
+        {rules && page === 'lobbies' && (
+          <Lobbies section={hash.split('/')[1]} onOpen={(entry) => { setLoadRequest(entry); window.location.hash = 'creator' }} />
+        )}
         {page === 'account' && <Account user={username} onLogout={logout} />}
       </main>
     </>