feat: Add AI SDK integration guide and direct server integration documentation

- Introduced a comprehensive guide for integrating MCPC with the AI SDK, detailing transport-based and direct server integration methods.
- Added prerequisites and setup instructions for running an MCPC server.
- Provided examples for connecting to the AI SDK using stdio transport and utilizing MCPC tools with automatic schema discovery and type-safe definitions.
- Created a new document for direct server integration, highlighting benefits, setup patterns, and complete examples.
- Implemented `convertToAISDKTools` function in the core package to facilitate the conversion of MCPC server tools to AI SDK compatible format.
- Added tests for the AI SDK adapter to ensure proper functionality and tool execution.

Author: yaonyan