fix: registration form — phone mask, required fields, snake_case body

- Address and phone now required (frontend + backend)
- Phone input mask: +7 (XXX) XXX-XX-XX
- Fix Bad Request: register body now sends snake_case keys
  (req() converts camelCase→snake_case, backend schema updated to match)

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

backend/src/routes/auth.ts

@@ -89,11 +89,11 @@ const auth: FastifyPluginAsync = async (fastify) => {
   // ── POST /api/auth/register ────────────────────────────────────────────────
   fastify.post<{
     Body: {
-      hotelName: string
-      address?: string
+      hotel_name: string
+      address: string
       contact: string
       email: string
-      phone?: string
+      phone: string
       password: string
     }
   }>(
@@ -102,20 +102,20 @@ const auth: FastifyPluginAsync = async (fastify) => {
       schema: {
         body: {
           type: 'object',
-          required: ['hotelName', 'contact', 'email', 'password'],
+          required: ['hotel_name', 'address', 'contact', 'email', 'phone', 'password'],
           properties: {
-            hotelName: { type: 'string', minLength: 2 },
-            address:   { type: 'string' },
-            contact:   { type: 'string', minLength: 2 },
-            email:     { type: 'string' },
-            phone:     { type: 'string' },
-            password:  { type: 'string', minLength: 8 },
+            hotel_name: { type: 'string', minLength: 2 },
+            address:    { type: 'string', minLength: 2 },
+            contact:    { type: 'string', minLength: 2 },
+            email:      { type: 'string' },
+            phone:      { type: 'string', minLength: 5 },
+            password:   { type: 'string', minLength: 8 },
           },
         },
       },
     },
     async (request, reply) => {
-      const { hotelName, address, contact, email, phone, password } = request.body
+      const { hotel_name: hotelName, address, contact, email, phone, password } = request.body
 
       if (!/[a-zA-Zа-яА-ЯёЁ]/.test(password)) {
         return reply.code(400).send({ error: 'Пароль должен содержать хотя бы одну букву' })