feat: add WiFi authorization module

- Backend: hotel_wifi_settings table (migration 046), CRUD routes
- Public API endpoint /api/wifi-auth/verify for captive portal
- Auth methods: room+lastname, room+birthdate, room+any, room_only
- Frontend: WiFiPage with settings, token management, setup guide
- Guide tabs: MikroTik, UniFi, Universal with copy-paste instructions
- Sidebar: WiFi item in Settings group

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

backend/migrations/046_wifi_settings.sql

@@ -0,0 +1,15 @@
+-- WiFi Auth module settings per hotel
+CREATE TABLE IF NOT EXISTS hotel_wifi_settings (
+  id            UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+  hotel_id      UUID        NOT NULL REFERENCES hotels(id) ON DELETE CASCADE,
+  enabled       BOOLEAN     NOT NULL DEFAULT false,
+  api_token     TEXT        NOT NULL DEFAULT encode(gen_random_bytes(32), 'hex'),
+  auth_method   TEXT        NOT NULL DEFAULT 'room_any',
+  -- room_lastname | room_birthdate | room_any | room_only
+  ssid_name     TEXT,
+  welcome_text  TEXT        DEFAULT 'Добро пожаловать! Введите данные для подключения к Wi-Fi.',
+  session_hours INT         NOT NULL DEFAULT 24,
+  created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  UNIQUE (hotel_id)
+);