Remove unused Device model item

TODO.md

@@ -2,7 +2,6 @@
 
 - server list sorting method / explain what the % number is (stability)
 - spam alt+shift+a when starting app on server browser → segfault
-- remove items.Device
 - register tab for sso servers?
 - cursor shape in HBox/HTabbedBox pages over fields
 - login with account already added → infinite spinner in room list

src/backend/models/items.py

@@ -351,16 +351,3 @@ class Event(ModelItem):
             return json.dumps(source_dict)
 
         return super().serialize_field(field)
-
-
-@dataclass
-class Device(ModelItem):
-    """A matrix user's device. This class is currently unused."""
-
-    id:             str  = field()
-    ed25519_key:    str  = field()
-    trusted:        bool = False
-    blacklisted:    bool = False
-    display_name:   str  = ""
-    last_seen_ip:   str  = ""
-    last_seen_date: str  = ""