fix(v4): support filters on wrapped relations

[BayBreezy]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Models using Strapi 4 response wrappers for relations reject valid filters such as parent.slug. The filter type followed data.attributes from the response structure. A v4-specific filter type now accepts direct relation fields while retaining existing accepted typings. These queries typecheck without casts; runtime requests are unchanged. Fixes #494.

Verified: lint, typecheck, all 44 tests, build, and strict checks of the generated declarations. Regression coverage includes recursive/nullable relations, compatibility, invalid inputs, and query serialization.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes (if not applicable, please state why)

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxtjs/strapi@559

commit: 63e4bb4