Auditing mobile/responsive views turned up two classes of bug:
1. Missing .table-responsive wrapper (token.ejs and profile.ejs's other
table already had it): admin.ejs (2 tables), invites.ejs (6 columns),
notifications.ejs (5 columns), users.ejs (7 columns — the worst case).
Without it these overflow the page horizontally on narrow viewports
instead of scrolling within the table.
2. groups.ejs's search/sort/count toolbar was a plain `d-flex` (no
flex-wrap) containing a search input, a <select> with a hard
min-width:175px, and a nowrap count span — on a narrow viewport
there's nowhere for that content to go but off-screen. Added
flex-wrap and gave the search input a flex-basis so it wraps onto
its own line first when space is tight.
Verified: EJS compiles for all five templates, npm test 192/192 pass,
and fetched each route from a running instance to confirm the fixes
are present in the served HTML.