chore(graph): remove SignalProcessor

- process_signal reads the rating with parse_rating; the adapter ignored the model it was given

tests/test_rating_integrity.py

@@ -75,13 +75,13 @@ def test_the_memory_log_records_review_rather_than_a_tradeable_hold(tmp_path):
 @pytest.mark.unit
 def test_the_signal_and_the_log_agree_on_the_same_decision(tmp_path):
     from tradingagents.agents.utils.memory import TradingMemoryLog
-    from tradingagents.graph.signal_processing import SignalProcessor
+    from tradingagents.agents.utils.rating import parse_rating
 
     log = TradingMemoryLog({"memory_log_path": str(tmp_path / "m.md")})
     for text in (INVERTED, REFUSAL, "**Rating**: Buy\n\nAccumulate."):
         log.store_decision("NVDA", f"2026-01-0{len(log.load_entries()) + 1}", text)
 
-    signals = [SignalProcessor.process_signal(None, text)
+    signals = [parse_rating(text)
                for text in (INVERTED, REFUSAL, "**Rating**: Buy\n\nAccumulate.")]
     assert [e["rating"] for e in log.load_entries()] == signals
 
@@ -121,8 +121,8 @@ def test_the_cli_says_when_a_run_produced_no_usable_rating(monkeypatch, tmp_path
             pass
 
         def process_signal(self, text):
-            from tradingagents.graph.signal_processing import SignalProcessor
-            return SignalProcessor.process_signal(None, text)
+            from tradingagents.agents.utils.rating import parse_rating
+            return parse_rating(text)
 
         def get_graph_args(self, callbacks=None):
             return {}