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>

src/lib/api.ts

@@ -175,13 +175,21 @@ export const api = {
 
     register: (data: {
       hotelName: string
-      address?: string
+      address: string
       contact: string
       email: string
-      phone?: string
+      phone: string
       password: string
     }) =>
-      req<{ ok: boolean; message: string }>('POST', '/api/auth/register', data),
+      // Snake_case вручную — req() конвертирует camelCase→snake_case автоматически
+      req<{ ok: boolean; message: string }>('POST', '/api/auth/register', {
+        hotel_name: data.hotelName,
+        address:    data.address,
+        contact:    data.contact,
+        email:      data.email,
+        phone:      data.phone,
+        password:   data.password,
+      }),
 
     forgotPassword: (email: string) =>
       req<{ ok: boolean }>('POST', '/api/auth/forgot-password', { email }),