Add support for protocol version 2025 06 18 (#54)

* Add basic support for 2025-06-18 header

* Remove json-rpc batch support

* Extend _meta and ajson slash in key support

* Add title to more entries

* Annotations, meta, output schema, structured outpu

* Update documentation for 2025-06-18

* Update demos 

* Update changelog

Merge branch 'main' of https://github.com/abap-ai/mcp

5 full testsuite for the mcp server (#6)

* Add testsuite with MCP typescript SDK

Simplifications to support downport