[Feature Request] Improve zoom and page navigation controls in the document viewer

Description With the changes introduced in Paperless-ngx 3.4.0 (#14485), the zoom and page navigation controls are now permanently displayed as an overlay at the bottom of the document viewer, directly on top of the document. Personally, I find this a little inconvenient, as the controls can obscure parts of the document depending on its layout. This can be particularly distracting when viewing scanned documents or pages with content close to the edges. Even when selecting the "Fit to page" option, the zoom and page navigation controls remain visible and continue to overlap the document. Suggested improvements I have two suggestions that could improve the user experience: 1. Show controls only when needed: Would it be possible to hide the zoom and page navigation controls by default and only display them when needed? On desktop devices, this could be achieved by showing the controls when hovering the mouse over the document. For mobile devices and other tou…