fix(initial-implementation): resolve P2/P3 cross-phase build issues

Three minimal fixes to make Marathon.sln build with 0/0:

1. Marathon.Infrastructure.csproj — add InternalsVisibleTo for
   Marathon.Infrastructure.Tests so test code can reference internal
   repository and exporter classes (Phase 2 issue blocking Phase 3 tests).
2. EventOddsParserTests.cs — add 'using Marathon.Domain.ValueObjects' so
   MatchScope/PeriodScope resolve.
3. RoundTripTests.cs — add 'using Microsoft.EntityFrameworkCore' so the
   ExecuteSqlRawAsync extension method on DatabaseFacade resolves.

Phase 5's anticipated LocalizationOptions / Serilog issues were already
resolved by its agent before being killed — no changes needed there.

Build status: 0 warnings, 0 errors.
Test status: Domain 96/96, UI 11/11, Infrastructure 42/77 (35 failing —
parser fixture issues + a real DateTimeOffset bug; reviewer will assess).

src/Marathon.Infrastructure/Marathon.Infrastructure.csproj

@@ -25,4 +25,8 @@
     <ProjectReference Include="..\Marathon.Application\Marathon.Application.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <InternalsVisibleTo Include="Marathon.Infrastructure.Tests" />
+  </ItemGroup>
+
 </Project>

tests/Marathon.Infrastructure.Tests/Persistence/RoundTripTests.cs

@@ -4,6 +4,7 @@ using Marathon.Domain.Enums;
 using Marathon.Domain.ValueObjects;
 using Marathon.Infrastructure.Persistence;
 using Marathon.Infrastructure.Persistence.Repositories;
+using Microsoft.EntityFrameworkCore;
 
 namespace Marathon.Infrastructure.Tests.Persistence;
 

tests/Marathon.Infrastructure.Tests/Scraping/EventOddsParserTests.cs

@@ -1,5 +1,6 @@
 using FluentAssertions;
 using Marathon.Domain.Enums;
+using Marathon.Domain.ValueObjects;
 using Marathon.Infrastructure.Scraping.Parsers;
 using Microsoft.Extensions.Logging.Abstractions;