Refactor logging configuration to use AppData directory

- Updated config.example.json to set default log_file to null.
- Modified config.py to resolve log file paths relative to the AppData directory.
- Added methods to get default log directory and log file path in AppData.
- Ensured logging behavior is consistent whether a log_file is specified or not.

.env.example

@@ -10,7 +10,8 @@ WEBAPP_URL=file:///./webapp/index.html
 
 # Logging
 LOG_LEVEL=DEBUG
-LOG_FILE=logs/webdrop_bridge.log
+# LOG_FILE defaults to AppData/Roaming/webdrop_bridge/logs/webdrop_bridge.log if not set
+# LOG_FILE=logs/webdrop_bridge.log
 ENABLE_LOGGING=true
 
 # Security - Path Whitelist