fix(memory): skip non-dict history.jsonl lines when reading

nanobot/agent/memory.py

@@ -433,9 +433,11 @@ class MemoryStore:
                     line = line.strip()
                     if line:
                         try:
-                            entries.append(json.loads(line))
+                            parsed = json.loads(line)
                         except json.JSONDecodeError:
                             continue
+                        if isinstance(parsed, dict):
+                            entries.append(parsed)
 
         return entries
 
@@ -453,7 +455,8 @@ class MemoryStore:
                 lines = [line for line in data.split("\n") if line.strip()]
                 if not lines:
                     return None
-                return json.loads(lines[-1])
+                parsed = json.loads(lines[-1])
+                return parsed if isinstance(parsed, dict) else None
         except (FileNotFoundError, json.JSONDecodeError, UnicodeDecodeError):
             return None