Major UX improvements across multiple pages

Шахматка:
- Date/period picker dropdown on navigation button (choose start date + days window)
- Cancelled bookings fade out with animation after 1 second

Бронирования:
- Clickable column headers with sort asc/desc (Гость, Заезд, Выезд, Статус, Источник, Сумма)

Страница входа:
- Removed role-based account selector — just email + password
- System auto-detects role/hotel from credentials

Настройки:
- New "Бронирование" section with room assignment strategy (spread/together/sequential/manual)
- Notifications: SMTP email config + SMS provider config (SMSC, SMS.ru, МТС, etc.)

Модули:
- Added Housekeeping and Channel Manager as proper modules
- Channel Manager lists: Booking.com, Airbnb, Яндекс Путешествия, Островок, Суточно.ру, OneTwoTrip
- Housekeeping visible to all roles (including housekeeper) via module status
- Sidebar now uses module status to show/hide Уборка and Каналы

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

backend/Dockerfile

@@ -0,0 +1,16 @@
+# ── Stage 1: Build ──────────────────────────────────────────────────────────
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm install
+COPY . .
+RUN npm run build
+
+# ── Stage 2: Run ────────────────────────────────────────────────────────────
+FROM node:20-alpine
+WORKDIR /app
+COPY --from=builder /app/dist        ./dist
+COPY --from=builder /app/node_modules ./node_modules
+COPY migrations ./migrations
+EXPOSE 3000
+CMD ["node", "dist/server.js"]