Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request?

Copied config-related types over from the eslint package into @eslint/core

What changes did you make? (Give an overview)

• Updated package.json files in packages/compat, packages/config-helpers, and packages/migrate-config to move @eslint/core to the dependencies section, ensuring it is available at runtime. [1] [2] [3]
• Replaced eslint type imports with @eslint/core in packages/compat/src/fixup-rules.js, packages/compat/src/ignore-file.js, packages/config-helpers/src/define-config.js, packages/config-helpers/src/global-ignores.js, packages/config-helpers/src/types.ts, and packages/migrate-config/src/migrate-config.js. This includes updates to typedefs like Config, Plugin, RuleEntry, and others to their corresponding @eslint/core counterparts. [1] [2] [3] [4] [5] [6]
• Renamed or adjusted type aliases for improved consistency, such as RuleEntry to RuleConfig and Linter.Config to ConfigObject. [1] [2]
• Updated @typescript-eslint/array-type to enforce consistent array type definitions in TypeScript files. The rule is configured to use generic for default array types and array for readonly arrays.

Related Issues

fixes #226

Is there anything you'd like reviewers to focus on?