Validate that directive applications are on valid locations

[glen-84]

Summary

• Adds DirectiveIsInValidLocationRule to HotChocolate.Types.Validation: a directive application at a location its definition does not declare is now reported as HCV0032. Applications without a definition are skipped, since DirectiveIsDefinedRule already reports those.
• DirectiveEvent now carries the DirectiveLocation at which the directive is applied, supplied by SchemaValidator at each publish site, since the location cannot be inferred from the member alone (arguments and input fields are both IInputValueDefinition). This is a breaking change to the public DirectiveEvent record struct.
• Apollo Federation preprocessing now attaches its synthesized @internal, @lookup, @is, @shareable, @require, and @external applications to the FusionBuiltIns.SourceSchemaDirectives definitions instead of detached placeholder definitions, so the applications carry the declared locations the new rule checks.

Test plan

• New DirectiveIsInValidLocationRuleTests with a failing case per type-system location (schema, scalar, object, interface, union, enum, enum value, input object, input field, field, field argument, directive definition, and directive-definition argument), plus declared-locations, repeatable, and undefined-directive controls.
• dotnet test src/HotChocolate/Core/test/Types.Validation.Tests: 632/632 pass.
• dotnet test src/HotChocolate/Fusion/test/Fusion.Composition.Tests: 3160/3160 pass.

[Copilot]

Pull request overview

Adds schema-validation coverage to ensure directives are only applied at locations declared by their definitions, and updates eventing + Fusion Federation preprocessing so synthesized directives carry correct declared locations for validation.

Changes:

• Introduces DirectiveIsInValidLocationRule (HCV0032) and registers it in the default SchemaValidator rule set.
• Extends DirectiveEvent to include the applied DirectiveLocation, and updates SchemaValidator to publish directive events with explicit locations.
• Updates Fusion Apollo Federation transformations to attach synthesized directive applications to FusionBuiltIns.SourceSchemaDirectives definitions (instead of placeholder directive definitions).

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/HotChocolate/Fusion/src/Fusion.Composition/ApolloFederation/TransformRequiresToRequire.cs	Uses built-in directive definitions for synthesized @require / @external applications so declared locations are available during validation.
src/HotChocolate/Fusion/src/Fusion.Composition/ApolloFederation/GenerateLookupFields.cs	Uses built-in directive definitions for synthesized @internal, @lookup, @is, @shareable applications.
src/HotChocolate/Core/test/Types.Validation.Tests/SchemaValidatorTests.cs	Updates default-rule registration expectations to include the new rule.
src/HotChocolate/Core/test/Types.Validation.Tests/Rules/DirectiveIsInValidLocationRuleTests.cs	Adds targeted tests for valid/invalid directive placement across type-system locations.
src/HotChocolate/Core/src/Types.Validation/SchemaValidator.cs	Publishes DirectiveEvent with explicit directive application locations across schema members.
src/HotChocolate/Core/src/Types.Validation/Rules/DirectiveIsUniqueRule.cs	Updates directive-event deconstruction to account for the new location payload.
src/HotChocolate/Core/src/Types.Validation/Rules/DirectiveIsInValidLocationRule.cs	Adds the new validation rule that emits HCV0032 for invalid directive application locations.
src/HotChocolate/Core/src/Types.Validation/Rules/DirectiveIsDefinedRule.cs	Updates directive-event deconstruction to account for the new location payload.
src/HotChocolate/Core/src/Types.Validation/Properties/ValidationResources.resx	Adds localized resource string for the new HCV0032 message.
src/HotChocolate/Core/src/Types.Validation/Properties/ValidationResources.Designer.cs	Regenerates resource accessor for the new message string.
src/HotChocolate/Core/src/Types.Validation/Logging/LogEntryHelper.cs	Adds log entry builder for “directive in invalid location” (HCV0032).
src/HotChocolate/Core/src/Types.Validation/Logging/LogEntryCodes.cs	Adds HCV0032 constant.
src/HotChocolate/Core/src/Types.Validation/Events/ValidationEvents.cs	Extends DirectiveEvent with DirectiveLocation to support location-aware rules.

Files not reviewed (1)

• src/HotChocolate/Core/src/Types.Validation/Properties/ValidationResources.Designer.cs: Generated file

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[github-actions]

Patch coverage

98.6% of changed lines covered (71/72)

File	Covered	Changed	Patch %
…/HotChocolate/Core/src/Types.Validation/SchemaValidator.cs	31	32	96.9% 🟡
…/Core/src/Types.Validation/Events/ValidationEvents.cs	2	2	100.0% 🟢
…/Core/src/Types.Validation/Logging/LogEntryHelper.cs	12	12	100.0% 🟢
…/Core/src/Types.Validation/Rules/DirectiveIsDefinedRule.cs	1	1	100.0% 🟢
…/src/Types.Validation/Rules/DirectiveIsInValidLocationRule.cs	11	11	100.0% 🟢
…/Core/src/Types.Validation/Rules/DirectiveIsUniqueRule.cs	1	1	100.0% 🟢
…/Fusion.Composition/ApolloFederation/GenerateLookupFields.cs	4	4	100.0% 🟢
…/ApolloFederation/TransformRequiresToRequire.cs	3	3	100.0% 🟢
…/Fusion/src/Fusion.Composition/SourceSchemaParser.cs	6	6	100.0% 🟢

Uncovered changed lines (JSON)

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  "sha": "4a70274a152721b49e3e1e7e99f724a2fa1a91b3",
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    { "path": "src/HotChocolate/Core/src/Types.Validation/SchemaValidator.cs", "ranges": [[252, 252]] }
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Project coverage: 56.3% (264451/470033 lines)