migrateLegacyPdfiumLocator

Corrects a PDF locator persisted by the Pdfium navigator before the page-index fix, by re-resolving it from this publication's position list.

The Pdfium navigator used to report page positions one too high: a stored locations.position is actual page + 1, and the page fragment and progressions are shifted accordingly.

Only use this API when you are upgrading and migrating the locators (bookmarks, reading progression) stored in your database, and only for locators created by the Pdfium navigator — locators your app computed itself from positions() are unaffected. Apply it once per stored locator. See the migration guide for more information.