Repair room filter, performance improvements

Chnaging delegate heights is a terrible idea that leads to graphic bugs.
Handle filtering (both room and accounts) and collapsing from a function
that sets the JsonListModel source.

src/python/app.py

@@ -84,7 +84,6 @@ class App:
         rl  = self.run_in_loop             # noqa
         ba  = self.backend                 # noqa
         mo  = self.backend.models          # noqa
-        smo = self.backend.sidepane_model  # noqa
         cl  = self.backend.clients
         tcl = lambda user: cl[f"@test_{user}:matrix.org"]  # noqa
 

src/python/models/items.py

@@ -13,12 +13,17 @@ class Account(ModelItem):
     display_name:    str      = ""
     avatar_url:      str      = ""
     profile_updated: datetime = field(default_factory=datetime.now)
+    filter_string:   str      = ""
 
     def __lt__(self, other: "Account") -> bool:
         name       = self.display_name or self.user_id[1:]
         other_name = other.display_name or other.user_id[1:]
         return name < other_name
 
+    # @property
+    # def filter_string(self) -> str:  # TODO: support serializing properties
+        # return " ".join((self.user_id, self.display_name))
+
 
 @dataclass
 class Room(ModelItem):