Missing lastModified field for McpSchema#Annotations 

Add missing `lastModified` field to the [McpSchema#Annotations](https://github.com/modelcontextprotocol/java-sdk/blob/a0afdcd493fcd3add9dd4cb75c4a9304e8461f95/mcp-core/src/main/java/io/modelcontextprotocol/spec/McpSchema.java#L649) to align with the [MCP Annotations type](https://modelcontextprotocol.io/specification/2025-06-18/schema#annotations)



