SDK client now holds control requests and MCP messages until initialize has been written

The SDK is the kit for driving Claude Code from your own program. Its Query class opens with an initialize message, and it now holds everything else until that message has been written:

• request() waits for initialize, and fails at once with "Query closed before response received" once the query has been cleaned up
• control_cancel_request is sent only if the original request actually went out
• streamInput waits for initialize
• messages from SDK MCP servers (tool providers run inside your program) go through writeAfterInitialize
• late replies to a manifest capture are dropped
• removing a server rejects its pending requests