Fix PageInfo Shareable Directive with Apollo Federation

[michaelstaib]

Fixes #9798

[Copilot]

Pull request overview

This PR fixes a schema-startup crash when using Apollo Federation together with implementation-first paging fields that return PageConnection<T> (issue #9798). The core change ensures the @shareable directive type is registered whenever a discovered PageInfo object type is backed by a runtime type implementing IPageInfo, not only when the built-in PageInfoType is used.

Changes:

• Update FederationTypeInterceptor.RegisterMoreTypes to detect and handle runtime PageInfo types (IPageInfo) and register ShareableDirective accordingly.
• Add a focused implementation-first regression test project that reproduces the crash and snapshots the resulting schemas for both Apollo Federation and Composite Source Schema paths.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/HotChocolate/ApolloFederation/src/ApolloFederation/FederationTypeInterceptor.cs	Registers ShareableDirective when a discovered page-info type is runtime-backed by IPageInfo, preventing directive resolution failures during schema completion.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/PageConnectionFederationTests.cs	Regression test ensuring schema builds with .AddApolloFederation() + implementation-first PageConnection<T> field.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/PageConnectionCompositeSchemaTests.cs	Companion test ensuring composite schema defaults also build successfully for the same paging scenario.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/EmployeeQuery.cs	Minimal implementation-first query using [UseConnection] and returning PageConnection<Employee> to reproduce #9798.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/Employee.cs	Minimal entity type for the paging tests.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/ModuleInfo.cs	Declares the module name used by the types source generator (ImplementationFirstTypes).
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/HotChocolate.ApolloFederation.ImplementationFirst.Tests.csproj	New test project wiring analyzers/source-gen and required references.
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/snapshots/PageConnectionFederationTests.PageConnection_Field_With_ApolloFederation_Builds_Schema.graphql	Snapshot asserting the federation schema output (including @shareable on PageInfo fields).
src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/snapshots/PageConnectionCompositeSchemaTests.PageConnection_Field_With_CompositeSourceSchema_Builds_Schema.graphql	Snapshot asserting composite schema output (including @shareable behavior for composite).
src/HotChocolate/ApolloFederation/HotChocolate.ApolloFederation.slnx	Adds the new implementation-first test project to the Apollo Federation solution.

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