Convex MCP server

# JS Runtime Environment There are a few ways user code can interact with our system. 1. There's a global `Convex` object that's created very early in `initialization::setup_context` and populated soon after when executing `setup.js`. We pass this global object as the first argument to all UDFs. 2. The `Convex.syscall` method, installed in `initialization::setup_context` and implemented within `syscalls.rs` provides the API for the user to interact with the database. 3. Helpers within `setup.js` provide bindings, like `Convex.get` for interacting with the database without having to use `Convex.syscall` directly. 4. The user can also import system modules under `convex:/system` that will eventually include code derived from our npm package. For example, we'll eventually have a custom `Int64` object that will be available for the user to create themselves within UDF execution. # Argument and return value serialization (as of 2021-11-10) ``` Arguments Return value ┌───────────────────┐ ┌───────────────────┐ │ Convex Value (JS) │ │ Convex Value (JS) │ └───────────────────┘ └───────────────────┘ │ ▲ convexReplacer │ │ convexReviver Browser ▼ │ ┌──────────────────────────┐ ┌──────────────────────────┐ │ JSON-serializable object │ │ JSON-serializable object │ └──────────────────────────┘ └──────────────────────────┘ │ ▲ JSON.serialize │ │ JSON.parse ▼ │ ┌─────────────┐ ┌─────────────┐ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┤ String ├ ─ ─ ─ ─ ─ ─ ─ ─ ┤ String ├ ─ ─ ─ ─ ─ ─ ─ ─ ─ └─────────────┘ └─────────────┘ │ ▲ serde::Deserialize │ │ serde::Serialize ▼ │ ┌──────────────────────┐ ┌──────────────────────┐ Rust │ Convex Value (Rust) │ │ Convex Value (Rust) │ └──────────────────────┘ └──────────────────────┘ │ ▲ serde::Serialize │ │ serde::Deserialize ▼ │ ┌────────────────┐ ┌────────────────┐ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┤ String │─ ─ ─ ─ ─ ─ ─ ┤ String │─ ─ ─ ─ ─ ─ ─ ─ ─ └────────────────┘ └────────────────┘ │ ▲ JSON.parse │ │ JSON.serialize ▼ │ ┌──────────────────────────┐ ┌──────────────────────────┐ │ JSON-serializable object │ │ JSON-serializable object │ └──────────────────────────┘ └──────────────────────────┘ │ ▲ convexReviver │ V8 │ convexReplacer ▼ │ ┌───────────────────┐ ┌───────────────────┐ │ Convex Value (JS) │ │ Convex Value (JS) │ └───────────────────┘ └───────────────────┘ │ ▲ │ │ │ ┌─────────────────────┐ │ │ │ │ │ └───▶│ User UDF code │────┘ │ │ └─────────────────────┘ ```