Switch to Velocity from Bungeecord and add configuration support

- Replaced Bungeecord proxy with Velocity proxy.
- Updated brand name and logging for Velocity support.
- Introduced `velocity` and `velocity-secret` configuration options.
- Removed deprecated Bungeecord handling.
- General refactor and cleanup for proxy integration.

.idea/misc.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" project-jdk-name="corretto-17" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" project-jdk-name="21" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>