[Fusion] Include internal types/fields during source schema validation

[glen-84]

Summary of the changes (Less than 80 chars)

• [Fusion] Include internal types/fields during source schema validation.

[Copilot]

Pull request overview

Updates Fusion composition so source schema validation also processes internal types/fields, aligning validation behavior with what can exist in source schemas (even if internal members are excluded from the final composed schema).

Changes:

• Removed filtering that previously skipped internal object types and internal output fields during source schema validation event publishing.
• Updated the k6 eShop.Reviews benchmark schema/resolver to make an internal @lookup field nullable (matching lookup validation guidance).
• Added/updated the benchmark gateway Fusion archive (gateway.far) to reflect the current benchmark composition inputs.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
src/HotChocolate/Fusion/src/Fusion.Composition/SourceSchemaValidator.cs	Publishes validation events for all types/fields (including internal) so rules can validate internal members too.
src/HotChocolate/Fusion/benchmarks/k6/eShop.Reviews/schema.graphqls	Makes Query.product nullable to satisfy lookup-return-type validation for an internal lookup field.
src/HotChocolate/Fusion/benchmarks/k6/eShop.Reviews/ProductQueries.cs	Aligns resolver nullability with the updated schema (Product?).
src/HotChocolate/Fusion/benchmarks/k6/eShop.Gateway/gateway.far	Adds/updates the gateway configuration archive used by the k6 benchmark gateway.

Comments suppressed due to low confidence (1)

src/HotChocolate/Fusion/src/Fusion.Composition/SourceSchemaValidator.cs:50

• This change alters SourceSchemaValidator to also publish events for internal types/fields; there are existing rule unit tests under Fusion.Composition.Tests, but none appear to assert that internal types/fields are included in source schema validation. Add a targeted test case (e.g., an @internal @lookup field returning a non-null type) to ensure the expected warnings/errors are produced for internal members and to prevent regressions.

            foreach (var type in schema.Types)
            {
                PublishEvent(new TypeEvent(type, schema), context);

                if (type is MutableComplexTypeDefinition complexType)
                {
                    PublishEvent(new ComplexTypeEvent(complexType, schema), context);

                    foreach (var field in complexType.Fields)
                    {
                        PublishEvent(new OutputFieldEvent(field, type, schema), context);

                        foreach (var argument in field.Arguments)
                        {
                            PublishEvent(
                                new FieldArgumentEvent(argument, field, type, schema), context);
                        }
                    }

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (58d2bd0) to head (6836530).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #9554   +/-   ##
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