[nai62]

• Directly opened images in dual view now appear with their final page count and layout, without showing a single-page preview first. Single view keeps its existing preview-before-folder-scan path.
• Read the folder list and await image loads asynchronously, reuse cached volumes, and defer normal prefetch until the initial display has painted. Apply the same spread rules to cold and cached folders, rescan stale listings, and reveal the startup window on load failure.
• Add regressions for first-page and wide-image exceptions, the last page, sorting, subfolders, EXIF orientation, CPU resizing, a one-image cache, broken and missing files, superseded requests, associated files, folder-item targets, and startup reveal. Document the Windows visual checks in developer/Testing.md.
• Verified the final commit with scripts\verify-windows.cmd debug on Windows: exit code 0; all 10 suites passed, with 663 passed, 0 failed, and 0 skipped. No compiler warnings. The pre-commit C++ formatting check passed for all 6 changed C++ files.
• The 9 QWARN messages are expected diagnostics from existing invalid-SVG and broken-AVIF tests. Interactive Windows checks for the visible transition, fullscreen, and slow folders have not been run.