[Fusion] Match abstract type conditions in fetch result path walkers

[michaelstaib]

fixes #10045

[Copilot]

Pull request overview

Fixes Fusion fetch-result path walking so inline-fragment type conditions can match abstract types (interfaces/unions) against concrete runtime __typename, addressing #10045 and preventing lookups from being skipped when reached through interface fragments.

Changes:

• Updated FetchResultStore path walking to treat inline-fragment type conditions as abstract-capable and perform subtype/union-member matching.
• Added planning tests to ensure lookup targets keep abstract type conditions when reached through interface fragments.
• Added execution tests + snapshots covering interface inheritance chains and union source-path narrowing by type condition.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Results/FetchResultStore.cs	Implements subtype-aware inline-fragment matching for both target and source path walkers.
src/HotChocolate/Fusion/test/Fusion.Execution.Tests/Planning/InterfaceInheritanceLookupPlanningTests.cs	Adds regression tests validating abstract vs concrete type conditions in planned fetch targets.
src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/InterfaceInheritanceExecutionTests.cs	Adds execution-level coverage for interface inheritance + union lookups/type conditions.
src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/snapshots/InterfaceInheritanceExecutionTests.Execution_Should_ResolveUnionMemberField_When_LookupNarrowsSourcePathByTypeCondition.yaml	Snapshot for union source-path narrowing behavior.
src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/snapshots/InterfaceInheritanceExecutionTests.Execution_Should_ResolveProduct_When_LookupReachedThroughTopLevelInterfaceFragment.yaml	Snapshot for top-level interface fragment lookup execution.
src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/snapshots/InterfaceInheritanceExecutionTests.Execution_Should_ResolveProduct_When_LookupReachedThroughNestedInterfaceHierarchy.yaml	Snapshot for nested interface hierarchy lookup execution.
src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/snapshots/InterfaceInheritanceExecutionTests.Execution_Should_ResolveProduct_When_LookupReachedThroughDirectIntermediateInterfaceFragment.yaml	Snapshot for direct intermediate interface fragment lookup execution.

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