feat(SEP-973): add support for icons and websiteUrl across relevant types

[alexhancock]

Motivation and Context

Implementing support for SEP-973 as requested in #417

Adds

• Icons for server implementations (multiple sizes supported)
• Icons for individual resources, tools, and prompts
• Website URLs for documentation linking

How Has This Been Tested?

• Unit testing

Will also

• Test in Goose
• Verify all additions have been made and tested

Breaking Changes

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

[Copilot]

Pull Request Overview

This PR implements SEP-973 support by adding icon and website URL capabilities across the MCP Rust SDK types. It extends the existing data models to support visual representation and documentation linking for servers, resources, tools, and prompts.

Key changes:

• Adds Icon struct for standardized icon representation with multiple format support
• Extends Implementation type with icons and website_url fields for server metadata
• Adds icon support to Tool, Resource, and Prompt types for individual component branding

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
crates/rmcp/src/model.rs	Introduces Icon struct and extends Implementation with icons/website_url fields
crates/rmcp/src/model/tool.rs	Adds icons field to Tool struct
crates/rmcp/src/model/resource.rs	Adds icons field to RawResource struct
crates/rmcp/src/model/prompt.rs	Adds icons field to Prompt struct
examples/servers/src/sampling_stdio.rs	Updates example to include icons field
examples/clients/	Updates client examples with new Implementation fields
crates/rmcp-macros/	Updates proc macros to support icons in tool/prompt attributes
test files	Updates JSON schemas and test files to reflect new fields

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[4t145]

Looks good to me