feat: migrate golangci-lint from v1 to v2 (#144)

Migrate golangci-lint from v1 to v2.

## Motivation and Context
The golangci-lint has been upgraded to v2 since March 2025.
The v2 of golangci-lint has simplified the linters management.

## How Has This Been Tested?
Tested locally with golangci-lint@v2.1.6

## Breaking Changes
No.

## Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

---------

Co-authored-by: haokunt <haokunt@opera.com>
Co-authored-by: Avinash Sridhar <sridharavinash@users.noreply.github.com>
Co-authored-by: Adam Jones <adamj+git@anthropic.com>

README.md

@@ -29,9 +29,9 @@ The MCP Registry service provides a centralized repository for MCP server entrie
 - Docker (optional, but recommended for development)
 
 For development:
-- golangci-lint v1.61.0 - Install with:
+- golangci-lint v2.3.1 - Install with:
   ```bash
-  curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.61.0
+  curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v2.3.1
   ```
 
 ## Running