Chat message edit, feature parity with flutter interface

backend/database.py

@@ -82,7 +82,7 @@ class Message(Base):
 
     # Identifier of the sender: user / system / user-$ID / agent-$ID
     sender: Mapped[str]
-    # Timestamp of this message
+    # Timestamp when this message was sent
     time: Mapped[int]
     # Timestamp of this message's last edit
     #last_edit: Mapped[int]