feat: add Renovate custom regex manager for MCP server images in registry.json

[JAORMX]

Description

This PR adds a Renovate custom regex manager configuration to automatically detect and update Docker image versions in the pkg/registry/data/registry.json file.

Changes

• Added a new custom regex manager in renovate.json that:

  • Detects Docker image references in the "image" field of registry.json
  • Supports various Docker registry formats (Docker Hub, GitHub Container Registry, AWS ECR, Microsoft Container Registry, Quay.io, etc.)
  • Groups these updates under "mcp server images" for better organization

• Updated the existing "dockerfile template base images" package rule to properly scope it to template files only

Benefits

• Automated dependency updates for MCP server Docker images
• Grouped updates for easier review and management
• Consistent with existing Renovate configuration patterns in the project

[amirejaz]

Wondering if updating the image might affect tools or metadata. If so, should we update those too? (Not sure how, though.)

[JAORMX]

This is a good point. We have some thv subcommands to get tools and such, so perhaps we should start leveraging them. I'm not sure yet how to run custom commands with Renovate, so I'll research that or implement it with gh actions.