Replace Super-Linter with MegaLinter

[ulises-jeremias]

Summary

Replace the repository Super-Linter workflow with a MegaLinter workflow and root configuration.

Context

NaNLABS is standardizing public repository linting on MegaLinter. This repository still uses super-linter/super-linter in .github/workflows/lint.yml.

Acceptance Criteria

• Remove or replace the Super-Linter workflow.
• Add .github/workflows/mega-linter.yml.
• Add .mega-linter.yml with diff-only validation for pull requests.
• Keep CI public-safe and avoid private/internal dependencies.
• Preserve equivalent lint coverage where practical.
• Upload MegaLinter reports as workflow artifacts.

Suggested Validation

• Use the MegaLinter CLI or documentation to scaffold the initial setup.
• Run YAML validation on the workflow.
• Open a PR and confirm MegaLinter reports status successfully.