Errors created by the SDK should be restricted to codes -32000 to -32099

[jspahrsummers]

This is the "server error" portion of the JSON-RPC error space, "reserved for implementation-defined server-errors."

Since MCP clients and servers are both JSON-RPC servers, it feels appropriate for the SDK to stay within this error code range—leaving the remaining error codes available for custom application usage.

[sumitesh9]

PR for this issue - #103