feat: support eslint 10

[oNo500]

Summary

• Upgrade devDependency eslint from v9 to v10
• Add peerDependencies field declaring support for ESLint >=8.40.0
• Remove @types/eslint (ESLint 10 ships its own types)
• Update @eslint/js and @eslint/json to v10/v1 to match ESLint 10
• Mark legacy configs.recommended (eslintrc format) as @deprecated — not supported by ESLint 10
• Fix Rule.RuleListener handler type: cast node: unknown to MemberNode inside handler body
• Update eslint-plugin-eslint-plugin import to fix ESM exports path in v7

Closes #60

Test plan

• npm run build:js — TypeScript compiles without errors
• npm run lint — no lint errors
• npm test — all 40 tests pass