fix: bypass broken Nexus, use nuget.org + local proto build

- NuGet.config: nuget.org for standard packages, local nupkg for proto
- Dockerfile: COPY nupkg/ before restore
- CI: build proto from CMS source before Docker build

src/FrontOffice.Main/Dockerfile

@@ -1,8 +1,9 @@
 FROM 194.5.195.53:32082/dotnet/sdk:9.0 AS build
 WORKDIR /src
 
-# Copy NuGet config and project file
+# Copy NuGet config, local packages, and project file
 COPY ["FrontOffice.Main/NuGet.config", "NuGet.config"]
+COPY ["nupkg/", "nupkg/"]
 COPY ["FrontOffice.Main/FrontOffice.Main.csproj", "FrontOffice.Main/"]
 
 # Restore dependencies