[Feature Request] Remember/default to "Preview" tab on mobile document detail view

Description Description On desktop, the document detail view shows metadata and the PDF/image preview side-by-side, so both are visible at once. On mobile (narrow viewport), this collapses into tabs, and the view always opens on the "Details" (metadata) tab first — the user has to tap over to "Preview" every time to see the actual document. Use case For documents where the content itself is the thing you want to check at a glance (e.g. a receipt, invoice, or scanned letter), the metadata tab isn't useful as a landing tab — the preview is. Right now there's no way to change this, so every single document open on mobile costs an extra tap. Suggested behavior Add a user setting (or a simple per-session remembered choice) that lets the document detail view on mobile default to the "Preview" tab instead of "Details." Ideally: whichever tab the user last viewed becomes the default for next time, or a static toggle in Settings…