Keyboard shortcuts (page/column navigation)

### Description

For people who prefer keyboard navigation, it might be nice to be able to use the arrow keys (or whichever keys are preferred) to move between pages & columns

No files or tests are named. Start by locating the page and column navigation entry points in the dashboard, then trace how focus and navigation currently work. Done means keyboard shortcuts move predictably between pages and columns without breaking existing navigation, with coverage for the supported key behavior if the project has relevant tests.

Written by the indexing model from the issue text.