fix: Add completions capability to Everything server

[morinokami]

Description

Added completions capability to the Everything server.

Related: modelcontextprotocol/typescript-sdk#268

Server Details

• Server: everything
• Changes to: capabilities

Motivation and Context

Following spec update #173, servers that support completions are now required to set the completions capability. Updated the Everything server implementation accordingly to reflect that it supports completions.

How Has This Been Tested?

Verified via the Inspector that completions and other server capabilities are functioning correctly.

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 Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

[olaservo]

Thanks!