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/app/api/open-day-register/route.ts

@@ -1,7 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import {
   addOpenDayBooking,
-  isOpenDayClassBookedByPhone,
   getPersonOpenDayBookings,
   getOpenDayEvent,
 } from "@/lib/db";
@@ -35,11 +34,6 @@ export async function POST(request: NextRequest) {
       return NextResponse.json({ error: "Телефон обязателен" }, { status: 400 });
     }
 
-    // Check not already booked
-    if (isOpenDayClassBookedByPhone(classId, cleanPhone)) {
-      return NextResponse.json({ error: "Вы уже записаны на это занятие" }, { status: 409 });
-    }
-
     const id = addOpenDayBooking(classId, eventId, {
       name: cleanName,
       phone: cleanPhone,