Map internal symbols to correct LSP kinds

[Widthdom]

Summary

• Add one exhaustive ordinal mapping from every registered internal symbol kind to LSP SymbolKind and CompletionItemKind, including module-shaped imports and conservative unknown/plugin fallbacks.
• Route document symbols, workspace symbols, and completion items through the same full-symbol mapping.
• Refine persisted callable and enum shapes into constructors and enum members only when their language metadata supports that interpretation, including compact/named constructors and escaped identifiers while rejecting same-name methods and ordinary constructor functions.
• Add decoded protocol-response coverage plus real extractor fixtures across TypeScript, Kotlin, Solidity, Java, Swift, Dart, Visual Basic, Pascal, C#, and Shell.

Root cause and impact

The three LSP surfaces projected broad persisted kinds through incomplete or separate mappings, and some paths did not retain the semantic metadata needed to distinguish constructors and enum members. This caused imports to appear as variables, constructors as functions, and language-specific enum entries to use inconsistent kinds. The shared mapping now keeps all three surfaces aligned.

Validation

• dotnet build CodeIndex.sln --no-restore — passed with 0 warnings and 0 errors.
• Issue-specific mapping test — passed on net8.0 and net9.0.
• Full LspServerTests class — 120/120 passed on both net8.0 and net9.0.
• dotnet format CodeIndex.sln --no-restore --verify-no-changes — passed.
• dotnet run --project tools/CodeIndex.Changelog -- check — validated all 41 fragments.
• git diff --check — passed.
• Full solution test run completed with only the pre-existing unrelated watcher timing failure RunCore_SubprojectObservesAncestorIgnoreFileChanges_Issue4592: net9.0 had 10,300 passed / 420 skipped / 1 failed; net8.0 had 10,774 passed / 7 skipped / 1 failed. The Issue Map internal symbols to correct LSP symbol and completion kinds #4870 tests and complete LSP test class pass independently on both targets.

Adversarial review

• Round 1 identified constructor metadata and cross-language enum-entry shape gaps; all findings were addressed with extractor-backed regressions.
• Round 2 identified over-broad constructor keyword handling, Java return-typed same-name methods, and C# verbatim constructor/enum identifiers; all four findings were addressed and validated.
• The repository workflow limit of two adversarial review rounds was observed.

Documentation and changelog

• Updated the English and Japanese LSP mapping contract in DEVELOPER_GUIDE.md.
• Updated the English and Japanese test contract in TESTING_GUIDE.md.
• Added bilingual fragment changelog.d/unreleased/4870.fixed.md.

Follow-ups

None within the requested issue scope.

Fixes #4870