unconditionally remove needsExtends from job serialization

Author: noxify

.changeset/needsextends-cleanup.md

@@ -0,0 +1,7 @@
+---
+"gitlab-ci-builder": patch
+---
+
+ensure `needsExtends` is always removed from final output
+
+Previously `needsExtends` (internal merge-order metadata) was only deleted in certain branches of the cleanup logic, causing it to leak into the final YAML when a job had a single remote `extends` reference. Now it's unconditionally removed from all jobs during serialization.

src/config.ts

@@ -558,15 +558,16 @@ export class Config {
 
         if (filtered.length === 0) {
           delete job.extends
-          delete job.needsExtends
         } else if (filtered.length === 1) {
           // Keep as string if only one extends remains (preserves original format)
           job.extends = filtered[0]
         } else {
-          delete job.needsExtends
           job.extends = filtered
         }
       }
+
+      // Always delete needsExtends as it's internal metadata
+      delete job.needsExtends
     }
   }