feat: scaffold monorepo with shared types and NestJS server

- pnpm workspace with packages/app, packages/server, packages/shared
- @mp-pilates/shared: enums, constants, TypeScript interfaces for all 8 data models
- @mp-pilates/server: NestJS bootstrap with health check, validation pipe, CORS
- Base TypeScript config with strict mode

packages/shared/src/index.ts

@@ -0,0 +1,52 @@
+// Enums
+export {
+  UserRole,
+  CardTypeCategory,
+  MembershipStatus,
+  TimeSlotStatus,
+  TimeSlotSource,
+  BookingStatus,
+  OrderStatus,
+} from './enums'
+
+// Constants
+export {
+  DEFAULT_CANCEL_HOURS_LIMIT,
+  DEFAULT_SLOT_CAPACITY,
+  SLOT_GENERATION_DAYS,
+  TIME_PERIODS,
+  DATE_SELECTOR_DAYS,
+  WEEKDAY_LABELS,
+} from './constants'
+
+// Types
+export type {
+  User,
+  UserProfileResponse,
+  UpdateProfileDto,
+  UserStatsResponse,
+  CardType,
+  CreateCardTypeDto,
+  UpdateCardTypeDto,
+  Membership,
+  MembershipWithCardType,
+  WeekTemplate,
+  WeekTemplateInput,
+  TimeSlot,
+  TimeSlotWithBookingStatus,
+  CreateManualSlotDto,
+  Booking,
+  BookingWithDetails,
+  CreateBookingDto,
+  Order,
+  OrderWithDetails,
+  CreateOrderDto,
+  PaymentParams,
+  CreateOrderResponse,
+  StudioConfig,
+  UpdateStudioConfigDto,
+  ApiResponse,
+  PaginatedData,
+  PaginatedResponse,
+  PaginationQuery,
+} from './types/index'