Convex MCP server

# Server This is the entry point for all of the code for use within query and mutation functions. This directory uses an "interface-impl" pattern where: - The main directory has all interfaces to define the types of the various abstractions. These are parameterized of the developers `DataModel` type and carefully written to only allow valid usage. - The `impl/` subdirectory has implementations of all of these interfaces. These implementations are sloppier about their types and **not parameterized over `DataModel`**. This simplifies their implementation and only gives up a bit of type safety. The `DataModel` type is built to help developers write correct code, not to check that our internal structures are correct.