feat(create-eslint-config): implement setup wizard

[hanna-skryl]

Partially addresses #47

Summary

• Interactive setup wizard for @code-pushup/eslint-config, triggered via npm init @code-pushup/eslint-config or imported programmatically
• Detects project state (deps, files, tsconfig, node version, existing eslint config) and pre-selects recommended configs
• Generates eslint.config.mjs (or .js for type: "module" projects) with preset inheritance
• Installs all required peer dependencies via the detected package manager
• Supports --yes, --configs, --tsconfig, --node-version-source, --node-version, and --dry-run CLI flags
• Full README with usage, options table, programmatic API, and available configs

Note

Merging into existing eslint.config.* files is not yet implemented. The wizard prints a snippet for the user to paste manually. Handling defineConfig and tseslint.config wrappers will ship in a follow-up. Relevant code is marked with TODO comments.