Simplify and restructure conditional logic in `SenderPdfImageEditor.razor` for better readability and maintainability. Merge redundant `else` blocks and reorganize rendering logic for page previews and fields.
Enhance PDF loading and page preview generation in `SenderEditorPage.razor`. Add error handling for failed page rendering, log warnings, and ensure consistent `_pageCount` initialization based on available data.
These changes improve code clarity, robustness, and maintainability.