remove: Delete incorrect Dockerfile from root

Workflow uses src/FrontOffice.Main/Dockerfile which is correct (nginx).
Root Dockerfile was using wrong runtime (aspnet instead of nginx).

Dockerfile

@@ -1,15 +0,0 @@
-FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
-WORKDIR /src
-COPY src/*.sln ./ 2>/dev/null || true
-COPY src/*/*.csproj ./
-RUN for file in *.csproj; do mkdir -p "${file%.*}" && mv "$file" "${file%.*}/"; done 2>/dev/null || true
-RUN dotnet restore "FrontOffice/FrontOffice.csproj" || dotnet restore
-COPY src/ ./
-RUN dotnet publish "FrontOffice/FrontOffice.csproj" -c Release -o /app/publish
-
-FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS runtime
-WORKDIR /app
-COPY --from=build /app/publish .
-ENV ASPNETCORE_URLS=http://+:8080
-EXPOSE 8080
-ENTRYPOINT ["dotnet", "FrontOffice.dll"]