[Server] Add meta parameter to addTool and addResource methods

[bb-c24]

Summary

Added meta parameter to addTool() and addResource() methods in the Server Builder to allow passing arbitrary metadata when manually registering tools and resources.

Motivation and Context

The internal array definitions for $tools and $resources already included meta: ?array<string, mixed> in their type definitions, but the corresponding addTool() and addResource() methods did not expose this parameter. This inconsistency meant that users could not pass metadata when manually registering tools and resources, even though the infrastructure to support it was already in place.

This change brings the public API in line with the internal data structures and provides feature parity with the discovery-based registration system.

How Has This Been Tested?

• Verified that the parameter is properly added to both methods
• Confirmed that the compact() calls include the new meta parameter
• Checked that PHPDoc annotations are correctly updated

Breaking Changes

None. This is a backward-compatible change as the meta parameter is optional and defaults to null.

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

Additional context

This change only affects the addTool() and addResource() methods. The addResourceTemplate() and addPrompt() methods also have meta in their array definitions but were not modified in this PR. These could be addressed in a follow-up PR if needed for consistency.

[chr-hertel]

Thank you @bb-c24!

[chr-hertel]

Can you please sign your commit @bb-c24 - thanks already!

[bb-c24]

@chr-hertel done, commit is now signed. Thank you.