[P0] Add GPL-3.0 copyright headers to all Java source files

[sfloess]

Problem

All Java source files are missing copyright and license headers, which is a GPL-3.0 compliance requirement.

Evidence

$ grep -r "Copyright" --include="*.java" . | wc -l
0

Impact

• Severity: HIGH
• Category: Legal/Compliance
• License compliance violation
• Legal ambiguity for contributors and users
• May prevent enterprise adoption

Required Action

Add standard GPL-3.0 copyright header to all .java files.

Priority

P0 - Critical - Must be fixed before v1.2 release.

Automation

Can be automated with Maven License Plugin or script.