Update devDependencies and migrate to ESLint 10 flat config (#168)

- Update @typescript-eslint/eslint-plugin and parser from 5.x to 8.58.1
- Update eslint from 8.x to 10.2.0 with new flat config format
- Update prettier from 2.x to 3.8.1, jest from 29.x to 30.3.0
- Update ts-jest to 29.4.9, typescript to 5.9.3, js-yaml to 4.1.1
- Update @types/jest to 30.0.0, jest-circus to 30.3.0
- Remove eslint-plugin-github, eslint-plugin-jest, eslint-plugin-prettier
  (incompatible with ESLint 10)
- Migrate .eslintrc.json to eslint.config.mjs (flat config)
- Remove .eslintignore (use ignores in flat config)
- Remove jest-circus testRunner config (default in Jest 30)
- Replace deprecated rules: no-empty-interface -> no-empty-object-type,
  remove no-var-requires (merged into no-require-imports),
  remove func-call-spacing/semi/type-annotation-spacing (removed in v8)

https://claude.ai/code/session_01K5K8LnpofCY12cksPpGDuj

Co-authored-by: Claude <noreply@anthropic.com>

Author: kyleconroy