Update December flights form and trip data

- Update form fields: Change 'Имя' to 'Фамилия, имя', add required phone field
- Add PDF upload for drone registration notice (BVS notice)
- Update trip conditions: Change 'Поездки с полетами дронов' to 'Дронослёты'
- Update submission deadline from 7 days to 5 days for drone flights
- Add detailed time departure info with location dependency
- Update privacy consent text and add centered consent header
- Hide November 2025 flights (set active: false)
- Update December 2025 flights image to winter drone photo
- Add backend validation for phone field and PDF file upload (max 5MB, PDF only)
- Update email notification function for consistent handling

static/data/upcoming-trips.json

@@ -9,7 +9,7 @@
       "meta": [
         "Выезд: рано утром (5-6 утра)"
       ],
-      "active": true,
+      "active": false,
       "order": 1
     },
     {
@@ -17,9 +17,9 @@
       "title": "Полёты в декабре 2025 года",
       "period": "Декабрь 2025",
       "description": "Зимние полёты выходного дня во Владимирской / Московской / Тверской области.",
-      "image": "https://s3.regru.cloud/sleeptrip-dev/images/Klin_20241005_1.jpg",
+      "image": "/static/images/Rassvet_20231202_9.webp",
       "meta": [
-        "Выезд: рано утром (5-6 утра)"
+        "Подача заявки минимум за 5 дней"
       ],
       "active": true,
       "order": 2