fix: LOW priority — GPU hints, CSRF cleanup, redundant query removal, mobile perf

- Add will-change to .hero-glow-orb (filter, transform) and .team-card-glitter::before (background-position)
- Clear CSRF cookie on logout alongside auth cookie
- Add max array length (100) validation on team reorder endpoint
- Remove redundant isOpenDayClassBookedByPhone pre-check (DB UNIQUE constraint handles it)
- Extract Schedule grid layout calculation into useMemo
- Reduce HeroLogo sparkle animations on mobile (15 → 8 via hidden sm:block)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/sections/Schedule.tsx

@@ -222,6 +222,20 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
     dispatch({ type: "SET_LOCATION", mode });
   }
 
+  const gridLayout = useMemo(() => {
+    const len = filteredDays.length;
+    const cls = len >= 7 ? "sm:grid-cols-2 lg:grid-cols-4 xl:grid-cols-7"
+      : len >= 6 ? "sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-6"
+      : len >= 4 ? "sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-5"
+      : len === 3 ? "sm:grid-cols-2 lg:grid-cols-3"
+      : len === 2 ? "sm:grid-cols-2"
+      : "justify-items-center";
+    const style = len === 1 ? undefined
+      : len <= 3 && len > 0 ? { maxWidth: len * 340 + (len - 1) * 12, marginInline: "auto" as const }
+      : undefined;
+    return { cls, style };
+  }, [filteredDays.length]);
+
   const activeTabClass = "bg-gold text-black shadow-[0_0_20px_rgba(201,169,110,0.3)]";
   const inactiveTabClass = "border border-neutral-300 text-neutral-500 hover:border-neutral-400 hover:text-neutral-700 dark:border-white/10 dark:text-neutral-400 dark:hover:text-white dark:hover:border-white/20";
 
@@ -349,8 +363,8 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
           {/* Desktop: grid layout */}
           <Reveal>
             <div
-              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}
+              className={`mt-8 hidden sm:grid grid-cols-1 gap-3 px-4 sm:px-6 lg:px-8 xl:px-6 ${gridLayout.cls}`}
+              style={gridLayout.style}
             >
               {filteredDays.map((day) => (
                 <div