Native DeepSeek review loop in periscope/src (Fase C2).

Live review_ic_async comes from review_session; PinScope validate.py and
validation_tools.py stay in dependency as _inherited_review_ic_async fallback.

tests/test_validation_trace_log.py

@@ -18,6 +18,7 @@ import pytest
 from pypdf import PdfWriter
 
 from backend.periscopex.utils import safe_mpn
+from backend.services import review_session as review_session
 from backend.services import validation as val
 from backend.services.llm.types import Completion, ToolCall, Usage
 from backend.services.storage import LocalStorageBackend
@@ -136,6 +137,7 @@ async def _run(ws, monkeypatch, before_ic):
         return await body(prov_cls(), "fake-model")
 
     monkeypatch.setattr(val, "call_with_fallback", fake_cwf)
+    monkeypatch.setattr(review_session, "call_with_fallback", fake_cwf)
 
     # The fake session needs the current ic_ref; thread it through by wrapping
     # review_ic_async to set the class attr before delegating.