Fix indexed configuration collection binding

[windischb]

Summary

• bind indexed configuration children to List<T> and one-dimensional arrays in numeric order
• accept JSON-array strings for collection targets while preserving numeric dictionary keys and byte[] behavior
• cover environment and Microsoft-adapter paths with regression tests and a runnable Microsoft-vs-Cocoar comparison
• finalize documentation and the complete changelog for 6.1.1
• update test/documentation build dependencies where compatible security fixes are available

Verification

• Release build succeeded for .NET 9 and .NET 10
• 779 .NET tests passed with the repository's CI filter; 4 explicitly skipped, 0 failed
• 5 TypeScript tests passed
• VitePress documentation build passed
• Microsoft binder / Cocoar environment / Cocoar adapter comparison passed with identical output
• all 11 NuGet packages packed successfully as 6.1.1
• NuGet vulnerability scan reported no vulnerable packages