chore: add Meta trademark / non-affiliation disclaimer to public footers

Per Meta's brand-use guidance for third-party products, sites that
reference WhatsApp must include a clear non-affiliation disclaimer in
the footer. Adds the standard line:

  "WhatsApp® is a registered trademark of Meta Platforms, Inc.
   Hostinger is not affiliated with, endorsed by, or sponsored by
   Meta Platforms, Inc."

Placed in:
- src/components/landing/footer.tsx — marketing footer (every public
  landing page).
- src/components/docs/shell.tsx — public docs pages had no footer at
  all; added a slim one carrying the same disclaimer.

Out of scope:
- Authed dashboard pages don't have a footer (full-screen workspace
  layout). The trademark-fair-use risk is concentrated on public
  surfaces — crawlers, visitors who haven't signed up, social shares.
  Skipping the dashboard keeps the workspace layout intact and the
  disclaimer where it does the most work.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/docs/shell.tsx

@@ -89,6 +89,14 @@ export function DocsShell({ pages, children }: DocsShellProps) {
 
         <main className="min-w-0 flex-1 py-10">{children}</main>
       </div>
+
+      <footer className="mt-10 border-t border-slate-800 bg-slate-950">
+        <div className="mx-auto w-full max-w-7xl px-4 py-6 text-xs leading-relaxed text-slate-600 sm:px-6">
+          WhatsApp® is a registered trademark of Meta Platforms, Inc.
+          Hostinger is not affiliated with, endorsed by, or sponsored by
+          Meta Platforms, Inc.
+        </div>
+      </footer>
     </div>
   )
 }

src/components/landing/footer.tsx

@@ -61,6 +61,11 @@ export function Footer() {
           <span>© {year} WaCRM. All rights reserved.</span>
           <span>Built on the official WhatsApp Business API.</span>
         </div>
+        <div className="mx-auto w-full max-w-7xl px-6 pb-5 text-xs leading-relaxed text-slate-600">
+          WhatsApp® is a registered trademark of Meta Platforms, Inc.
+          Hostinger is not affiliated with, endorsed by, or sponsored by
+          Meta Platforms, Inc.
+        </div>
       </div>
     </footer>
   )