Add mock database infrastructure for unit testing persistence code

[bero]

Summary

Added mock database infrastructure to enable unit testing of database-dependent Bold code without requiring a real database connection.

Changes

New Files

UnitTest/Code/Mocks/BoldMockDatabase.pas

• TBoldMockField - Mock implementation of IBoldField
• TBoldMockParameter - Mock implementation of IBoldParameter
• TBoldMockQuery - Mock implementation of IBoldQuery, IBoldExecQuery, IBoldDataSet, IBoldParameterized
• TBoldMockDatabase - Mock implementation of IBoldDatabase with transaction tracking
  UnitTest/Code/Mocks/Test.BoldMockDatabase.pas
• 7 example unit tests demonstrating mock usage

Usage Example

var
  MockDb: TBoldMockDatabase;
  Query: IBoldQuery;
begin
  MockDb := TBoldMockDatabase.Create;
  try
    // Configure mock data
    MockDb.MockQuery.SetFieldNames(['ID', 'Name', 'Value']);
    MockDb.MockQuery.AddRow([1, 'First', 100]);
    MockDb.MockQuery.AddRow([2, 'Second', 200]);
    // Use in tests
    Query := MockDb.GetQuery;
    Query.AssignSQLText('SELECT * FROM TestTable');
    Query.Open;
    
    Assert.AreEqual(2, Query.RecordCount);
    Assert.AreEqual(1, Query.FieldByName('ID').AsInteger);
    
    FMockDb.ReleaseQuery(Query);
  finally
    MockDb.Free;
  end;
end;

Technical Notes

Reference Counting

The mock classes disable Delphi's automatic interface reference counting by overriding _AddRef and _Release to return -1. This is because:

• Field and parameter objects are cached and reused
• Query and field lifetimes are managed by their parent objects
• Without this, interface variables going out of scope would cause premature object destruction

Field Caching

TBoldMockQuery caches TBoldMockField objects in an internal list rather than creating new ones per call to FieldByName. Field values are updated from the current row when navigating (First, Next).