style: clear whitespace, unused-import and blank-line lint

Strip trailing whitespace, drop unused imports/variables/global statements,
split multi-imports, fix E3xx/E1xx spacing and E712 comparisons. No behaviour
change; only E501 long lines remain in flake8.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

hbd/server/data.py

@@ -1,12 +1,14 @@
 msgs = []  # in-memory list of recent messages for new websocket clients; also logged to file via notify.eventlog
+
+
 class Data:
 
     def __init__(self, config):
         self.config = config
         self.data = {}
-    
+
     def update(self, new_data):
         self.data.update(new_data)
-    
+
     def get(self, key, default=None):
-        return self.data.get(key, default)
+        return self.data.get(key, default)