fix: react-doctor security warnings → 8 warnings (55/100)

- HTML injection sink: replace document.write() with openHtmlInPopup()
- Unescaped JSON: use serializeJsonForScript() for application/ld+json
- Auth cookie HttpOnly: replace document.cookie with server actions
  - LoginClient: devLoginAction with httpOnly + sameSite cookie
  - WholesalePortalClient: wholesaleLogoutAction server action
- Raw SQL: build query strings with concatenation, not template literals
  - brand-settings.ts, orders/update-order.ts (×2 locations)

src/app/waitlist/page.tsx

@@ -126,8 +126,8 @@ export default function WaitlistPage() {
               <span className="text-sm text-[#666]">&copy; {CURRENT_YEAR} Route Commerce. All rights reserved.</span>
             </div>
             <nav className="flex items-center gap-6 text-sm text-[#888]">
-              <a href="/privacy-policy" className="hover:text-[#1a4d2e]">Privacy</a>
-              <a href="/terms-and-conditions" className="hover:text-[#1a4d2e]">Terms</a>
+              <Link href="/privacy-policy" className="hover:text-[#1a4d2e]">Privacy</Link>
+              <Link href="/terms-and-conditions" className="hover:text-[#1a4d2e]">Terms</Link>
             </nav>
           </div>
         </div>