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/common/proto.py

@@ -8,17 +8,17 @@ Message Types:
     PLG: Plugin data message (client -> server)
 """
 
-from typing import Dict, Any, Union
+from typing import Dict, Any
 import json
 import zlib
 
 
 def encode_value(v: Any) -> str:
     """Encode a value for protocol transmission.
-    
+
     Args:
         v: Value to encode (int, float, str, bool, list, dict, etc.)
-        
+
     Returns:
         String representation suitable for protocol
     """
@@ -35,23 +35,23 @@ def encode_value(v: Any) -> str:
 
 def decode_value(val: str) -> Any:
     """Decode a value from protocol format.
-    
+
     Args:
         val: String value from protocol
-        
+
     Returns:
         Decoded Python object
     """
     if not val:
         return val
-    
+
     # Check for JSON-encoded complex types
     if val.startswith("@"):
         try:
             return json.loads(val[1:])
         except Exception:
             return val[1:]  # Return as string without @
-    
+
     # Try numeric conversion (avoid eval to prevent SyntaxWarnings on version strings)
     if val[0].isdigit() or (val[0] == '-' and len(val) > 1 and val[1].isdigit()):
         try:
@@ -63,7 +63,7 @@ def decode_value(val: str) -> Any:
         except ValueError:
             pass
         return val
-    
+
     return val
 
 
@@ -135,12 +135,12 @@ def oldmtodict(msg: bytes):
 
 def encode_plugin_data(plugin_name: str, data: Dict[str, Any]) -> bytes:
     """Encode plugin data into a PLG message.
-    
+
     Args:
         plugin_name: Name of the plugin (e.g., "os_info", "cpu_monitor")
         data: Plugin data dictionary
         compress: Whether to compress the payload
-        
+
     Returns:
         Encoded message bytes
     """
@@ -151,12 +151,11 @@ def encode_plugin_data(plugin_name: str, data: Dict[str, Any]) -> bytes:
 
 def decode_plugin_data(msg: bytes) -> Dict[str, Any]:
     """Decode a PLG message into plugin data.
-    
+
     Args:
         msg: Raw message bytes
-        
+
     Returns:
         Dictionary with 'ID', 'plugin', and plugin data fields
     """
     return stodict(msg)
-