fix (schedule): Setting tweaks and more bugfixes.

Add the schedule dashboard to the config dashboard.
Move the schedule cost to the second page.
Allow categories to be selected for the session room.

Fix an issue where blacklist role would be checked with no guild data.
Fix typos in session unloading.
Delay session notification.
More logging.

src/modules/schedule/core/timeslot.py

@@ -297,11 +297,10 @@ class TimeSlot:
                 for session in sessions
                 if session.lobby_channel is not None
             ]
-            notify_tasks = [
-                asyncio.create_task(session.notify())
-                for session in fresh
-                if session.lobby_channel is not None and session.data.opened_at is None
-            ]
+            # Trigger notify tasks
+            for session in fresh:
+                if session.lobby_channel is not None:
+                    session.notify()
 
             # Start lobby update loops
             for session in sessions:
@@ -317,7 +316,6 @@ class TimeSlot:
             async for task in limit_concurrency(voice_coros, 5):
                 await task
             await asyncio.gather(*message_tasks)
-            await asyncio.gather(*notify_tasks)
 
             # Write opened
             if fresh: