fix: clickable trainers in day cards, remove trainer dropdown, fix layout shift

- Remove trainer dropdown from filter bar — filter by clicking names in schedule cards
- Make trainer/type clickable in DayCard with gold highlight on active filter
- Fix showcase layout shift: track max detail height to prevent section from shrinking
- Remove key-based grid remount that re-triggered Reveal animations on filter change

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/sections/Schedule.tsx

@@ -283,7 +283,6 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
           {/* Desktop: grid layout */}
           <Reveal>
             <div
-              key={`${locationMode}-${filterTrainer}-${filterType}-${filterStatus}`}
               className={`mt-8 hidden sm:grid grid-cols-1 gap-3 px-4 sm:px-6 lg:px-8 xl:px-6 ${filteredDays.length >= 7 ? "sm:grid-cols-2 lg:grid-cols-4 xl:grid-cols-7" : filteredDays.length >= 6 ? "sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-6" : filteredDays.length >= 4 ? "sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-5" : filteredDays.length === 3 ? "sm:grid-cols-2 lg:grid-cols-3" : filteredDays.length === 2 ? "sm:grid-cols-2" : "justify-items-center"}`}
               style={filteredDays.length === 1 ? undefined : filteredDays.length <= 3 && filteredDays.length > 0 ? { maxWidth: filteredDays.length * 340 + (filteredDays.length - 1) * 12, marginInline: "auto" } : undefined}
             >