Parent controls for children, name-tile sign-in, restricted Learn search, simple mode

- Sign-in page shows name tiles on remembered devices; tap a name, then PIN or passkey
- Music and Movies are separate on the server; Plex can be locked to a child's managed profile
- Activity log, weekly summary and alerts to parents; per-area and weekend limits
- Requests from children (Ask button) answered in Settings; bonus screen time from rewards
- Restricted Learn search (Simple English Wikipedia, blocked words) replaces web search for children
- Simple mode (big-button home) for young children or grandparents
- Child usage kept in memory instead of read from disk on every request
- Tests and README updated

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

admin.js

@@ -26,7 +26,7 @@ async function handle(req, res, me) {
       const b = JSON.parse(await readBody(req) || '{}');
       if (u.id === me.id && b.disabled) return json(res, 400, { error: 'You cannot turn off your own account' });
       audit.log('person changed', { who: me.name, detail: u.name + (b.disabled !== undefined ? (b.disabled ? ' (turned off)' : ' (turned on)') : '') + (b.signOutEverywhere ? ' (signed out everywhere)' : '') + (b.tabs ? ' (tabs)' : '') + (b.role ? ' (role)' : '') }, req);
-      users.update(id, { name: b.name, tabs: b.tabs, role: b.role, disabled: b.disabled, signOutEverywhere: b.signOutEverywhere, kid: b.kid, board: b.board });
+      users.update(id, { name: b.name, tabs: b.tabs, role: b.role, disabled: b.disabled, signOutEverywhere: b.signOutEverywhere, kid: b.kid, board: b.board, simple: b.simple });
       return json(res, 200, { user: row(users.get(id)) });
     }
     if (!action && req.method === 'DELETE') {