Fix coverage with several contract classes; table annotation and file path checks; clean task dir on write

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014aUaQeLnwbb1zTpN7kHeat

tasks_gen/eval/G0121/seed/blends.tabl.abap

@@ -0,0 +1,7 @@
+@EndUserText.label : 'Roast total per blend'
+@AbapCatalog.enhancement.category : #NOT_EXTENSIBLE
+define table {{p}}blends {
+  key client : abap.clnt not null;
+  key blend  : abap.char(4) not null;
+  total_kg   : abap.dec(15,3);
+}