Bump version to 0.3.0-preview.2

Bump version number to 0.3.0 (#534)

Don't conflate request and response IDs in Streamable HTTP transports (…

…#475)

Update documentation of McpJsonUtilities.DefaultOptions. (#463)

Remove internal GetBase64Data helper (#422)

This can now just use DataContent.Base64Data.

Clean up namespaces (#410)

No meaningful code changes, just lots of namespace shuffling to have fewer namespaces and to put things in better namespaces.

Update to latest M.E.AI version (#401)

Remove batching support from StreamableHttpServerTransport (#372)

Improve testing for StreamableHttpHandler and IdleTrackingBackgroundS…

…ervice (#345)

* Add idle session pruning tests
* Remove redundant CTS from StreamableHttpHandler
  * StreamableHttpServerTransport.HandlePostRequest already creates the equivelant CTS
    which DeleteRequest_CompletesSession_WhichCancelsLongRunningToolCalls verifies
* Fix accept header validation for GET
* Use InvalidOperationException for transport-not-connected errors in doc comments
* Fix flaky Cancellation_ThrowsCancellationException test

Add server-side Streamable HTTP transport support (#330)

- Changes IJsonRpcMessage to an abstract base class so RelatedTransport will always be available
- Streamable HTTP supports multiple concurrent HTTP request with their own indpendent SSE response streams
- RelatedTransport indicates the source or destination of the JsonRpcMessage

- Changes the default RequestId to a JSON number for better compatibility with MCP servers in the wild