Address review: use footer_actions directly, restore panel-material-ui pin

Removed hasattr fallback for footer_actions/footer_objects since
panel-material-ui >=0.9.0 guarantees footer_actions. Restored the
pin that was accidentally lowered to >=0.8.1.

Author: ghostiee-11

lumen/ai/ui.py

@@ -1634,12 +1634,11 @@ async def _generate_follow_up():
 
         if len(self.interface):
             message = self.interface.objects[-1]
-            attr = "footer_actions" if hasattr(message, "footer_actions") else "footer_objects"
             existing = [
-                obj for obj in (getattr(message, attr) or [])
+                obj for obj in (message.footer_actions or [])
                 if getattr(obj, 'name', '') != "FollowUp"
             ]
-            setattr(message, attr, existing + [follow_up_button])
+            message.footer_actions = existing + [follow_up_button]
 
     def __panel__(self):
         return self._main

pixi.toml

@@ -20,7 +20,7 @@ lint = ["py312", "lint"]
 [dependencies]
 bokeh = "*"
 holoviews = ">=1.17.0"
-panel-material-ui = ">=0.8.1"
+panel-material-ui = ">=0.9.0"
 hvplot = "*"
 intake = "<2"
 jinja2 = ">3.0"