chore: remove admin and agent pipeline remnants

prisma/migrations/20260418191500_remove_discovery_pipeline/migration.sql

@@ -0,0 +1,13 @@
+DROP TABLE IF EXISTS project_discovery_tasks;
+
+DO $$
+BEGIN
+  IF EXISTS (
+    SELECT 1
+    FROM pg_type
+    WHERE typname = 'TaskStatus'
+  ) THEN
+    DROP TYPE "TaskStatus";
+  END IF;
+END
+$$;