Proposed service price fetched from the backend

[michalstruck]

Create a minimal supabase integration (should be possible to provide an anon key + link to fetch) on the landing page. The goal is to minimize JS as much as possible.
Requirements:

• The proposed monthly price is fetched from the backend (create a new table?schema?).
• We use as little js as possible, for this we can omit testing/staging environments and point straight to prod.
• Provide an error fallback for the price