feat: self-serve signup Phase 2 (frontend cutover) (#162)

Co-authored-by: Michael Chihlas <michael@resolutionflow.com>
Co-committed-by: Michael Chihlas <michael@resolutionflow.com>

frontend/src/pages/AccountSettingsPage.tsx

@@ -6,6 +6,7 @@ import {
   Check,
   Clock,
   Copy,
+  CreditCard,
   Crown,
   FolderTree,
   Loader2,
@@ -598,6 +599,12 @@ export function AccountSettingsPage() {
               title="Profile"
               description="Your name, email, and personal preferences"
             />
+            <SettingsRow
+              to="/account/billing"
+              icon={<CreditCard className="h-4 w-4" />}
+              title="Billing"
+              description="Subscription, payment method, and invoices"
+            />
           </div>
 
           {isAccountOwner && (