Summary

• add stable semantic binding identities populated at the TypeEnvironment declaration and lookup seams
• serve textDocument/definition for local value bindings in full language-feature mode only
• handle hoisting, shadowing, parameters, assignments, catch/loop bindings, classes, and overload declarations
• refuse unsafe property/member guesses until their complete semantic domain is indexed
• preserve the existing TypeChecker APIs and document the remaining navigation work

Scope

This is the next M3 slice of #1306: local value definition. Type-namespace bindings, import/re-export provenance, cross-module definition, references, safe rename, and Track D remain for follow-up work, so the epic stays open.

Verification

• dotnet build SharpTS.LanguageServer/SharpTS.LanguageServer.csproj --no-restore
• dotnet test SharpTS.Tests/SharpTS.Tests.csproj --no-restore --filter FullyQualifiedName~DefinitionServiceTests (12 passed)
• dotnet test SharpTS.Tests/SharpTS.Tests.csproj --no-restore --filter FullyQualifiedName~LanguageServer (63 passed before the final handler-only test addition)
• dotnet test SharpTS.Tests/SharpTS.Tests.csproj --no-restore --filter FullyQualifiedName~TypeChecker (1,412 passed)
• full suite: 16,216 passed

Refs #1306