Rust associated type defaults are not emitted for trait symbols

[Widthdom]

Summary

Extract_RustTraitAssociatedTypeDefaults_RecordsPropertySymbols fails because Rust trait declarations are indexed as protocol symbols, while the associated type default post-pass only scans interface containers.

Evidence

• PR Fix HTML class reference extraction #2599 CI failed on build (ubuntu-latest, net9.0) with CodeIndex.Tests.SymbolExtractorTests.Extract_RustTraitAssociatedTypeDefaults_RecordsPropertySymbols.
• The same failure reproduced locally when running dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj --filter FullyQualifiedName~SymbolExtractorTests after merging current origin/main.

Expected

Rust trait associated type defaults such as type Output = (); and type Error: std::error::Error = String; should be emitted as property symbols under the trait container.

[Widthdom]

Work started on branch fix-issue2101 as part of the CI fix for PR #2601.

[Widthdom]

Stopping work for PR #2601. The Rust associated type default fix is already present on the current main branch, so #2603 is no longer included in the #2601 scope.

[Widthdom]

Verifying the latest origin/main on branch fix-issue2603 to confirm whether this is already fixed. I will close this issue with the reproduction details if the reported test now passes and the expected associated type default symbols are covered.

[Widthdom]

Resuming work in PR #2601 because the latest PR pipeline still fails on CodeIndex.Tests.SymbolExtractorTests.Extract_RustTraitAssociatedTypeDefaults_RecordsPropertySymbols. The previous main-branch fix was not sufficient for the merge commit under CI.

[Widthdom]

Verified on latest origin/main (76d19f0) using branch fix-issue2603.

Reproduction/validation performed:

• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj --filter "FullyQualifiedName~SymbolExtractorTests.Extract_RustTraitAssociatedTypeDefaults_RecordsPropertySymbols" passed on both net8.0 and net9.0.
• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj --filter "FullyQualifiedName~SymbolExtractorTests" passed on both net8.0 and net9.0, with 1061 tests passing per target framework.
• Confirmed the existing test asserts Rust associated type defaults are emitted as property symbols under the trait's protocol container for Output and Error.

Conclusion: this issue is already fixed on current main, so closing as resolved.