fix(acms): replace contextlib suppress with direct import in __init__.py

The plan_execution_integration module exists and is always available.
The contextlib.suppress(ImportError) guard was dead code and caused
ACMSContextAssembler/PlanExecutionACMSIntegration to be conditionally
undefined when tests import from cleveragents.acms.__all__, triggering
unit_tests and integration_tests failures per ruff F821 rules.

Reviews #8414, #8415, #8469 requested this change across three passes.

ISSUES CLOSED: #9584

src/cleveragents/acms/__init__.py

@@ -13,8 +13,6 @@ Based on ``docs/specification.md`` ~lines 42333-42422, 44405-44420.
 
 from __future__ import annotations
 
-import contextlib
-
 from cleveragents.acms import uko as _uko
 from cleveragents.acms.context_policy_loader import (
     ContextPolicyConfig,
@@ -22,13 +20,10 @@ from cleveragents.acms.context_policy_loader import (
     PolicyScope,
     ViewPolicyConfiguration,
 )
-
-with contextlib.suppress(ImportError):
-    from cleveragents.acms.plan_execution_integration import (
-        ACMSContextAssembler,
-        PlanExecutionACMSIntegration,
-    )
-
+from cleveragents.acms.plan_execution_integration import (
+    ACMSContextAssembler,
+    PlanExecutionACMSIntegration,
+)
 from cleveragents.acms.uko import (
     CODE_DETAIL_LEVEL_MAP,
     FUNC_DETAIL_LEVEL_MAP,