fix(test): correct patch target for CorrectionService in M3 e2e helper

The CorrectionService import in plan.py is a lazy import inside the
correct() function body, so it does not exist as a module-level attribute.
Patch the class at its definition site instead:
  cleveragents.application.services.correction_service.CorrectionService

Fixes CI integration_tests failure for PR #439.

robot/helper_m3_e2e_verification.py

@@ -550,7 +550,7 @@ def correction_dry_run() -> None:
 
     with (
         patch(
-            "cleveragents.cli.commands.plan.CorrectionService",
+            "cleveragents.application.services.correction_service.CorrectionService",
             return_value=mock_correction_svc,
         ),
         patch(