Resource and ResourceTemplate are missing the title field #296

Summary

The MCP specification (2025-11-25) defines an optional title field for Resource
and ResourceTemplate, but the PHP SDK does not implement it.

Spec definition

The Resources specification
lists the following fields for Resource:

• uri: Unique identifier for the resource
• name: The name of the resource.
• title: Optional human-readable name of the resource for display purposes.

Example from the spec:

{
  "uri": "file:///project/src/main.rs",
  "name": "main.rs",
  "title": "Rust Software Application Main File",
  "description": "Primary application entry point",
  "mimeType": "text/x-rust"
}

ResourceTemplate follows the same pattern:

{
  "uriTemplate": "file:///{path}",
  "name": "Project Files",
  "title": "📁 Project Files",
  "description": "Access files in the project directory"
}

All four server capability types in the spec define title as the optional
human-readable display label:

Current SDK behaviour

Mcp\Schema\Resource and Mcp\Schema\ResourceTemplate have no title constructor
parameter, no title property, and do not include title in jsonSerialize().
Servers that want to expose a human-readable label for a resource currently have no
way to do so.

Additionally, the docblock for Resource::$name currently reads:

A human-readable name for this resource. This can be used by clients to populate
UI elements.

This description conflicts with the spec, where name is a short identifier (e.g.
"main.rs") and title is the human-readable display label.

Proposed fix

Add public readonly ?string $title = null to both Resource and ResourceTemplate,
include it in fromArray() and jsonSerialize(), and update the $name docblock to
match the spec.