[release/10.0] Guard EF file generation during commandline builds to fix AOT build fork bomb (#38403)

Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

Author: Copilot

src/EFCore.Design/Design/Internal/DbContextOperations.cs

@@ -303,7 +303,10 @@ private IReadOnlyList<string> PrecompileQueries(
 
         try
         {
-            workspace = MSBuildWorkspace.Create();
+            // Set _EFGenerationStage to a non-empty value so that the design-time build performed by
+            // OpenProjectAsync below doesn't re-trigger the EF file generation targets. Otherwise the
+            // generation targets would invoke this operation again, resulting in a fork bomb.
+            workspace = MSBuildWorkspace.Create(new Dictionary<string, string> { ["_EFGenerationStage"] = "build" });
             workspace.LoadMetadataForReferencedProjects = true;
 #pragma warning disable CS0612 // Obsolete
 #pragma warning disable CS0618 // Obsolete

src/EFCore.Tasks/buildTransitive/Microsoft.EntityFrameworkCore.Tasks.targets

@@ -166,7 +166,7 @@ For Publish:
        This target has the same Inputs and Outputs as CoreCompile to run only if CoreCompile isn't going to be skipped -->
   <Target Name="_EFPrepareForCompile"
           DependsOnTargets="_EFProcessGeneratedFiles"
-          Condition="'$(_EFGenerationStage)'==''"
+          Condition="'$(_EFGenerationStage)'=='' And '$(DesignTimeBuild)' != 'True'"
           Inputs="$(MSBuildAllProjects);
                   @(Compile);
                   @(_CoreCompileResourceInputs);