- SiteInfo record added to Core/Models
- ISiteListService interface with GetSitesAsync signature
- SiteListService derives admin URL via Regex, connects via SessionManager
- Filters to Active sites only, excludes OneDrive personal (-my.sharepoint.com)
- Access denied ServerException wrapped as InvalidOperationException with actionable message
- DeriveAdminUrl marked internal static for unit testability
- InternalsVisibleTo added to AssemblyInfo.cs to expose internal to test project
- 2 DeriveAdminUrl tests pass; full suite: 53 pass, 4 skip, 0 fail
- SharePointPaginationHelper: async iterator with ListItemCollectionPosition loop (bypasses 5k limit); RowLimit=2000; [EnumeratorCancellation] for correct WithCancellation support
- ExecuteQueryRetryHelper: exponential backoff on 429/503/throttle; surfaces retry events via IProgress<OperationProgress>; max 5 retries
- LogPanelSink: custom Serilog ILogEventSink writing color-coded entries to RichTextBox via Dispatcher.InvokeAsync for thread safety
