fix(eslint-plugin-react-hooks): stabilize flat config typing and binding

[mrsandy1965]

Problem
eslint-plugin-react-hooks flat config typing used a cast + late mutation pattern ({} as ... + Object.assign), which can weaken strict TypeScript inference and was tied to reports of flat config typing friction.
Also, the flat config getters returned newly allocated objects on every access.

Solution
Refactored flat config construction to be strongly typed and circular-reference-safe without Object.assign, then memoized getter results to avoid repeated allocations.

Changes made

• Introduced explicit ReactHooksPlugin / flat config types for safer typing.
• Replaced configs.flat cast-and-assign initialization with typed getters.
• Corrected flat plugin map typing to use 'react-hooks'.
• Added local caches for:
  • recommended
  • recommended-latest
    so each object is created once and reused.
• Added regression test to assert flat presets:
  • bind to the plugin instance
  • reference the expected rules objects.

Testing performed

• yarn prettier
• yarn linc
• cd packages/eslint-plugin-react-hooks && yarn test --silent --no-watchman

Result: all package tests pass (5 suites, 5083 tests).