Refactor GetTransactionSummaryByMerchantReport to reduce cyclomatic complexity

[Copilot]

• Refactor GetTransactionSummaryByMerchantReport in ReportingManager.cs to reduce method length below 50 lines
  • Add private sealed class MerchantTransactionGroupProjection for the intermediate query result
  • Add private sealed class MerchantTransactionFinalProjection for the final query result
  • Extract BuildMerchantTransactionBaseQuery private static helper method
  • Extract BuildMerchantTransactionFinalQuery private static helper method
  • Simplified main method body to use the new helper methods (reduced from ~83 to ~44 lines)
• Fixed build error: missing closing brace } for MerchantTransactionFinalProjection class caused by merge conflict resolution from main

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Complexity] Method ReportingManager::GetTransactionSummaryByMerchantReport has 96 lines of code (limit is 50)</issue_title>
<issue_description>

Codacy ID: c6859b674165e0c220787e001f8c7381

File: EstateReportingAPI.BusinessLogic/ReportingManager.cs
Line: 752
Rule: Complexity (Warning)
Commit: 157eaa6a54cd58196a9963e70e66cb25c6c2873a

Message: Method ReportingManager::GetTransactionSummaryByMerchantReport has 70 lines of code (limit is 50)

**Code Snippet:**
```csharp
    public async Task<Result<TransactionSummaryByMerchantResponse>> GetTransactionSummaryByMerchantReport(TransactionQueries.TransactionSummaryByMerchantQuery request, 
```

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Complexity] Method ReportingManager::GetTransactionSummaryByMerchantReport has 96 lines of code (limit is 50) #425

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[StuartFerguson]

@copilot can you fix the build error please

[Copilot]

@copilot can you fix the build error please

Fixed in fbe33e1. The merge from main introduced a missing closing brace } for the MerchantTransactionFinalProjection class — TransactionDetailQueryResult (added in main) was inserted directly inside it without proper class separation.