New game_admin_game_new route/form (reuses AdminGameType, same pattern
as editing a game's total time) so games - including the 3 upcoming
Easy/Medium/Hard difficulty options - can be created through the admin
panel instead of needing a direct DB insert.
Also show each game's total time (in minutes) next to the player
count in the "Create New Session" dropdown, since that's the actual
difficulty signal players are choosing between - number of players
alone didn't convey it.
Difficulty itself needs no new session-level concept: each difficulty
is just a separate Game row with its own TOTAL_TIME setting, which
checkAllPlayersReady() already reads when starting the session's
timer. Hint timing depending on difficulty is separate, upcoming work.
The sidebar was a fixed 220px flex column that left barely any room
for content on a phone, and tables had no min-width so columns just
squeezed into unreadable slivers instead of scrolling.
Moves the sidebar's layout rules out of inline styles (which media
queries can't override) into real CSS classes, and collapses it into
a horizontally-scrollable pill bar below 768px so the content area
gets the full screen width. Tables now get a sensible min-width so
they scroll horizontally on narrow screens instead of squishing, and
the per-player tab bar on the session log view scrolls too.
Frank