Upgrade bundled TypeScript declarations to 6.0.3

[nickna]

Summary

• pin external/typescript and TypeScriptLibProvider.CompilerVersion to v6.0.3
• synchronize all 108 upstream lib*.d.ts files and the license, with an LF-stable SHA-256 manifest and repeatable update/check script
• support TypeScript 6 iterator rest binding patterns and test every bundled graph plus DOM/WebWorker combinations
• regenerate and review the v6.0.3 conformance baseline, add ES2024/ES2025 target selection, and document the preserved SharpTS defaults

Baseline review

The v6.0.3 baseline has 514 entries (151 Pass, 214 Fail, 141 ParseError, 8 Skipped). Relative to v5.5.4 it adds 8 paths, removes 1, and changes 183 common-path outcomes. Of those 183, 174 have changed upstream test sources; the remaining 9 all gained or changed upstream tsc error baselines.

Validation

• ./scripts/sync-typescript-libs.ps1
• dotnet build SharpTS.sln --configuration Release --no-restore
• dotnet test SharpTS.Tests/SharpTS.Tests.csproj --configuration Release --no-build --filter "Category!=LiveNetwork&Category!=LoadSensitive" (16,198 passed)
• dotnet test SharpTS.TypeScriptConformance/SharpTS.TypeScriptConformance.csproj --no-restore (45 passed)
• clean detached worktree with external/typescript uninitialized: dotnet build SharpTS.csproj --configuration Release --no-restore

Closes #1305