fix(extensions): initialize Application property in NestSummary

Set Application to "N/A" when converting from PepLib.Nest to satisfy
the required property constraint.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

PepApi.Core/Extensions.cs

@@ -60,7 +60,8 @@ namespace PepApi.Core
                 MaterialGrade = nest.MaterialGrade,
                 Notes = nest.Notes,
                 HasErrors = !nest.Errors.IsNullOrWhiteSpace(),
-                Revision = nest.UserDefined1
+                Revision = nest.UserDefined1,
+                Application = "N/A"
             };
         }
     }