fix(contribution-service): fix toRecordDto using wrong property name

- Changed `record.finalContribution` to `record.amount` for getting final contribution value
- Added optional chaining to prevent undefined errors
- Added default values for safety

The ContributionRecordAggregate uses `amount` property, not `finalContribution`.
This was causing "Cannot read properties of undefined (reading 'value')" errors.

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

backend/services/contribution-service/src/application/queries/get-contribution-account.query.ts

@@ -183,16 +183,16 @@ export class GetContributionAccountQuery {
 
   private toRecordDto(record: any): ContributionRecordDto {
     return {
-      id: record.id,
+      id: record.id?.toString() ?? '',
       sourceType: record.sourceType,
-      sourceAdoptionId: record.sourceAdoptionId,
+      sourceAdoptionId: record.sourceAdoptionId?.toString() ?? '',
       sourceAccountSequence: record.sourceAccountSequence,
       treeCount: record.treeCount,
-      baseContribution: record.baseContribution.value.toString(),
-      distributionRate: record.distributionRate.value.toString(),
+      baseContribution: record.baseContribution?.value?.toString() ?? '0',
+      distributionRate: record.distributionRate?.value?.toString() ?? '0',
       levelDepth: record.levelDepth,
       bonusTier: record.bonusTier,
-      finalContribution: record.finalContribution.value.toString(),
+      finalContribution: record.amount?.value?.toString() ?? '0',
       effectiveDate: record.effectiveDate,
       expireDate: record.expireDate,
       isExpired: record.isExpired,