Add FastAPI dashboard MVP

src/engram.py

@@ -66,12 +66,19 @@ class Correctness:
         return self.confirmations / total
 
     def to_dict(self) -> dict:
+        # Backwards/robustness: older code paths may have appended raw dicts.
+        review_history: List[dict] = []
+        for entry in self.review_history:
+            if isinstance(entry, dict):
+                review_history.append(entry)
+            else:
+                review_history.append(entry.to_dict())
         return {
             "confirmed": self.confirmed,
             "confirmations": self.confirmations,
             "rejections": self.rejections,
             "last_reviewed": self.last_reviewed,
-            "review_history": [r.to_dict() for r in self.review_history],
+            "review_history": review_history,
         }
 
     @classmethod