feat(marketing): add contact form submission and testing setup

- Add contact API endpoint for demo requests and sales enquiries
- Implement functional contact forms on Demo and Pricing pages with honeypot spam protection
- Update footer layout: remove Company section, add contact email
- Update self-hosted FAQ to mention open source with GitHub links
- Add vitest and testing-library dependencies
- Add tests for MarketingLayout and PricingPage components
- Remove placeholder external-auth test file

src/pages/auth/OIDCLoginPage.tsx

@@ -120,7 +120,7 @@ export default function OIDCLoginPage() {
         setErrorMsg(err.message);
         setStep("error");
       });
-  // eslint-disable-next-line react-hooks/exhaustive-deps
+   
   }, [oidcSessionId]);
 
   // ── Determine step once both context and auth state are ready ───────────────