feat: add maintenance tracking module foundation

Entities:
- MaintenanceSchedule: track preventive/corrective maintenance
- MaintenanceCost: record actual maintenance expenses

DTOs:
- CreateMaintenanceScheduleDto: schedule maintenance
- CreateMaintenanceCostDto: log costs
- UpdateMaintenanceScheduleDto: mark complete/adjust cost

Repository:
- getUpcomingMaintenance(): find due maintenance
- getMaintenanceCosts(): historical costs by date
- getTotalMaintenanceCost(): aggregate spending

Also fixed fuel-consumption.entity.ts: totalDistanceKm default 0

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

apps/edr-freight-api/src/modules/maintenance/dto/create-maintenance.dto.ts

@@ -0,0 +1,87 @@
+import { IsUUID, IsString, IsDateString, IsNumber, IsOptional, IsEnum } from 'class-validator';
+import { MaintenanceType, MaintenanceStatus } from '../entities/maintenance-schedule.entity';
+
+export class CreateMaintenanceScheduleDto {
+  @IsUUID()
+  vehicleId!: string;
+
+  @IsEnum(MaintenanceType)
+  maintenanceType!: MaintenanceType;
+
+  @IsString()
+  description!: string;
+
+  @IsDateString()
+  scheduledDate!: string;
+
+  @IsOptional()
+  @IsNumber()
+  estimatedCost?: number;
+
+  @IsOptional()
+  @IsString()
+  serviceProvider?: string;
+
+  @IsOptional()
+  @IsString()
+  notes?: string;
+
+  @IsOptional()
+  @IsNumber()
+  nextDueKm?: number;
+
+  @IsOptional()
+  @IsDateString()
+  nextDueDate?: string;
+}
+
+export class CreateMaintenanceCostDto {
+  @IsUUID()
+  vehicleId!: string;
+
+  @IsOptional()
+  @IsUUID()
+  maintenanceScheduleId?: string;
+
+  @IsDateString()
+  incurredDate!: string;
+
+  @IsNumber()
+  costAmount!: number;
+
+  @IsString()
+  costType!: string;
+
+  @IsString()
+  description!: string;
+
+  @IsOptional()
+  @IsString()
+  serviceProvider?: string;
+
+  @IsOptional()
+  @IsString()
+  invoiceNumber?: string;
+
+  @IsOptional()
+  @IsString()
+  notes?: string;
+}
+
+export class UpdateMaintenanceScheduleDto {
+  @IsOptional()
+  @IsEnum(MaintenanceStatus)
+  status?: MaintenanceStatus;
+
+  @IsOptional()
+  @IsDateString()
+  completedDate?: string;
+
+  @IsOptional()
+  @IsNumber()
+  actualCost?: number;
+
+  @IsOptional()
+  @IsString()
+  notes?: string;
+}