Adding a blog post announcing the official PHP SDK for MCP

Motivation and Context

This blog post announces the general availability of the official PHP SDK for MCP, developed in collaboration with the PHP Foundation and Symfony. It informs the community about this new SDK joining the MCP ecosystem.

How Has This Been Tested?

• Markdown formatting verified against existing blog posts (particularly 2025-07-31-governance-for-mcp.md)
• All links manually verified to be working

Breaking Changes

N/A - This is a blog post addition only

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 (N/A for blog post)
• I have added appropriate error handling (N/A for blog post)
• I have added or updated documentation as needed

Additional context

This blog post was created in collaboration with the the Anthropic MCP team, PHP Foundation and Symfony teams to announce the official PHP SDK release. The post follows the same format and style conventions as other announcement posts in the blog.