Page CSS files each carried their own copies of the same atomic margin
utilities (.mt-4, .mt-8, .mb-12, .ml-8, .my-10, ...). The definitions
were identical everywhere they appeared, with each file holding only
the subset it happened to need.
Move all of them into a single styles/utils.css imported once from
main.tsx, and delete the per-page copies from InboundFormModal,
CustomGeoSection, PanelUpdateModal, VersionModal, BasicsTab, NordModal,
OutboundFormModal, and WarpModal. The classes are available globally
on the panel app; login.tsx and subpage.tsx entries do not consume any
of them so they stay untouched.
