Chores: claim from the pool; admin picks who appears on the family board

- "Anyone" chores get Take it / Put back; a claimed chore is that person's for the day
- Per-person "Show on the family board" switch controls board tiles and family chore progress
- 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 });
+      users.update(id, { name: b.name, tabs: b.tabs, role: b.role, disabled: b.disabled, signOutEverywhere: b.signOutEverywhere, kid: b.kid, board: b.board });
       return json(res, 200, { user: row(users.get(id)) });
     }
     if (!action && req.method === 'DELETE') {