checkstyle.xml: enforce Java-style arrays

To quote Google's Java style guide:

> The square brackets form a part of the type, not the variable:
> String[] args, not String args[].

See: https://checkstyle.org/styleguides/google-java-style-20250426/javaguide.html

Author: alanorth

checkstyle.xml

@@ -106,6 +106,9 @@ For more information on CheckStyle configurations below, see: http://checkstyle.
         <!-- Right braces should be on start of a new line (default value) -->
         <module name="RightCurly"/>
 
+        <!-- Enforce Java-style array declaration instead of C-style -->
+        <module name="ArrayTypeStyle"/>
+
         <!-- ##### Indentation / Whitespace requirements ##### -->
         <!-- Require 4-space indentation (default value) -->
         <module name="Indentation"/>