Fix C# parameter modifier type references

[Widthdom]

Summary

• exclude C# out, ref, in, params, this, and scoped only when they occur in parameter/argument modifier positions
• preserve following concrete and generic type references across multiline, final-fragment, and nested-lambda layouts
• add extractor and indexed graph-query regressions plus bilingual documentation and changelog coverage

Root cause

Multiline continuation lines could fall through to the simple declaration type parser, whose leading-token scan did not recognize parameter modifiers. The initial bounded fix also stopped after top-level comma handling, while nested invocation/lambda arguments and final )-closing fragments required position-aware scanning across the full line.

Validation

• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj -c Release --no-build --filter FullyQualifiedName~Issue4832 -p:UseSharedCompilation=false — passed on net8.0 and net9.0 (2 tests each)
• dotnet build CodeIndex.sln -c Release --no-restore -p:UseSharedCompilation=false — passed with 0 warnings and 0 errors
• dotnet test CodeIndex.sln -c Release --no-build -p:UseSharedCompilation=false — passed: net8.0 10,511 passed / 7 skipped / 0 failed; net9.0 10,038 passed / 419 skipped / 0 failed
• dotnet run --project tools/CodeIndex.Changelog -- check — passed (6 fragments validated)
• full-workspace rebuilt index — lowercase C# out type_reference rows: 0
• Codex adversarial review round 1 found a multi-fragment continuation gap; fixed
• Codex adversarial review round 2 found nested-lambda and final-fragment gaps; both fixed, with targeted and full regressions passing afterward

Documentation and changelog

• updated the English and Japanese sections in DEVELOPER_GUIDE.md and TESTING_GUIDE.md
• added changelog.d/unreleased/4832.fixed.md
• no changes to AGENTS.md, CLAUDE.md, or AGENT_GUIDE.md

Fixes #4832