Replace printStackTrace() with proper java.util.logging

[sfloess]

Part of #27: Improve Error Handling and Logging

Scope

Replace all e.printStackTrace() and System.out.println() calls with proper java.util.logging.Logger usage across the entire codebase.

What to do

• Search for all printStackTrace(), System.out.println(), and System.err.println() in Java files
• Replace with Logger.getLogger(ClassName.class.getName()) and appropriate log levels
• Use Logger.log(Level.SEVERE, "message", exception) for exceptions
• Use Level.WARNING for recoverable issues, Level.INFO for operational events, Level.FINE/FINER for debug

Acceptance criteria

• Zero remaining printStackTrace() calls
• Zero remaining System.out/err.println() in production code (test code acceptable)
• All classes use a static Logger field with the class name
• Exception logging includes both message and exception object