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_no_tool_recovery.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
@@ -124,6 +125,7 @@ async def test_no_tool_calls_triggers_forced_submit_next_turn(workspace, monkeyp
         return await body(_Provider(), "fake-model")
 
     monkeypatch.setattr(val, "call_with_fallback", fake_cwf)
+    monkeypatch.setattr(review_session, "call_with_fallback", fake_cwf)
 
     orig = val.review_ic_async