package:dart_mcp v0.3.0

• Added error checking to required fields of all Request subclasses so that
  they will throw helpful errors when accessed and not set.
• Added enum support to Schema.
• Add more detail to type validation errors.
• Remove some duplicate validation errors, errors are only reported for the
  leaf nodes and not all the way up the tree.
  • Deprecated a few validation error types as a part of this, including
    propertyNamesInvalid, propertyValueInvalid, itemInvalid and
    prefixItemInvalid.
• Added a custom validation error type.
• Breaking: Auto-validate schemas for all tools by default. This can be
  disabled by passing validateArguments: false to registerTool.
• Updates to the latest MCP spec, 2025-06-08
  • Adds support for Elicitations to allow the server to ask the user questions.
  • Adds ResourceLink as a tool return content type.
  • Adds support for structured tool output.
• Breaking: Change MCPClient.connectStdioServer signature to accept stdin
  and stdout streams instead of starting processes itself. This enables custom
  process spawning (such as using package:process), and also enables the client
  to run in browser environments.
• Fixed a problem where specifying --log-file would cause the server to stop
  working.