Mark TopstepX accounts dead only off landed fills and settled books

The MLL floor no longer recomputes while a position is open or while
the balance disagrees with the books beyond fee noise — the last
settled floor stands, so balance ≤ floor can only come true when a
booked fill crosses a settled floor (Topstep's own liquidation fill
included). The floor also survives canTrade flipping off, so a blown
account stays ☠ instead of demoting to inactive.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/accounts/[id]/page.tsx

@@ -592,7 +592,7 @@ export default function AccountPage() {
                         <div>
                             <p className="font-bold text-sm">Account Blown</p>
                             <p className="text-slate-300 text-xs mt-0.5">
-                                Balance ${fmt(account.amount)} has breached the Tradovate auto-liquidation floor
+                                Balance ${fmt(account.amount)} has breached the auto-liquidation floor
                                 {liqFloor != null ? ` of $${fmt(liqFloor)}` : ''}.
                             </p>
                         </div>