feat(web): add public Manisa business landing page

[mhtcode]

Summary

• replace the anonymous root redirect with a public Manisa business landing page
• preserve automatic redirect to /dashboard for authenticated users
• match the existing management UI's dark/teal design system
• add About, Services, Address/Contact, Social Media, and Staff Login sections
• use the existing hair and nail service catalog to keep public copy relevant
• add deploy-time configuration for business address and social URLs

Configuration

Set these values in the web app environment for the real business details:

• NEXT_PUBLIC_BUSINESS_ADDRESS
• NEXT_PUBLIC_INSTAGRAM_URL
• NEXT_PUBLIC_TIKTOK_URL
• NEXT_PUBLIC_FACEBOOK_URL

If social URLs are not configured, the page shows a neutral placeholder instead of inventing links.

Notes

The private management login remains at /login; successful authenticated visitors to / continue directly to /dashboard.