fix: merge streamed chunks into final_state so reports save correctly

graph.stream() yields per-node deltas, not the full state. Taking
trace[-1] only captured the last node's contribution, so reports
saved to disk were missing every section except the final decision.
Merge all chunks in both the CLI path and trading_graph._run_graph's
debug branch.

#719 #736

cli/main.py

@@ -1154,8 +1154,11 @@ def run_analysis(checkpoint: bool = False):
 
             trace.append(chunk)
 
-        # Get final state and decision
-        final_state = trace[-1]
+        # Streamed chunks are per-node deltas, not full state. Merge them
+        # so every report field populated across the run is present.
+        final_state = {}
+        for chunk in trace:
+            final_state.update(chunk)
         decision = graph.process_signal(final_state["final_trade_decision"])
 
         # Update all agent statuses to completed