Add DataFactory.MCP.Core as submodule reference in Fabric.Mcp.Server

- Add DataFactory.MCP as git submodule at external/DataFactory.MCP
- Add project reference using $(RepoRoot) for portability
- Add Apache.Arrow 22.1.0 to Directory.Packages.props (only new dependency needed)
- Microsoft.Identity.Client and Microsoft.Extensions.Http already satisfied transitively
- Build verified: 0 warnings, 0 errors

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Ebram Tawfik

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "external/DataFactory.MCP"]
+	path = external/DataFactory.MCP
+	url = https://github.com/microsoft/DataFactory.MCP.git

Directory.Packages.props

@@ -3,6 +3,7 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
   <ItemGroup>
+    <PackageVersion Include="Apache.Arrow" Version="22.1.0" />
     <PackageVersion Include="Azure.Containers.ContainerRegistry" Version="1.2.0" />
     <PackageVersion Include="Azure.Communication.Sms" Version="1.0.2" />
     <PackageVersion Include="Azure.Communication.Email" Version="1.0.2" />

external/DataFactory.MCP

@@ -69,6 +69,8 @@
   <ItemGroup>
     <ProjectReference Include="$(RepoRoot)\core\Fabric.Mcp.Core\src\Fabric.Mcp.Core.csproj" />
     <ProjectReference Include="$(RepoRoot)\tools\Fabric.*\src\*.csproj" />
+    <!-- DataFactory.MCP.Core integration (via git submodule at external/DataFactory.MCP) -->
+    <ProjectReference Include="$(RepoRoot)external\DataFactory.MCP\DataFactory.MCP.Core\DataFactory.MCP.Core.csproj" />
   </ItemGroup>
 
   <ItemGroup>