Keep the navigation bar on the same fixed position to avoid accidental clicks into nodes

This may sound stupid but it happened so many times now. I often blindly click on the next button to browse through the nodes but the vertical position keeps on jumping up and down, until there are nodeboxes with a lot of text, so the navigation bar jumps all the way down and I accidentally click on a nodebox instead. Then I'm on the node page, when I click back I'm on the first page again.

This image shows the transition from page=5 to page=6. Notice how the mouse cursor stays on the same vertical position, but on the second page is hovering over a nodebox.

* Add additional navigation bar on the top, which is independent of the nodeboxes
* Make a fixed vertical position of the navigation bar on the bottom (either as floating, or by making the nodebox heights fixed, or add a smart-scroll towards the relative position of the previous page)
* Add the previous page to navigation history, so back button works correctly

No source files, tests, or entry points are named. Start by locating the component that renders the paginated node list and its navigation controls; clarify which proposed navigation behavior is wanted, then verify that navigation stays at a stable position and browser back returns to the prior page.

Written by the indexing model from the issue text.