chore: remove mcp-schema

[paoloricciuti]

Since we are not using the DB anymore, having the schema as a package is just confusing and unnecessary...we can clean up quite a bit by removing it.

WDYT @khromov ?

[khromov]

It depends a bit on what we see as the long-term plan for the MCP. If we add distilled docs, would we then commit it into the repo like use_cases?