Clean up build artifacts and migration files

- Remove generated JavaDoc documentation (doc/ directory)
- Remove Ant build artifacts and tools
- Remove IDE-specific files (.classpath, nbproject/)
- Remove migration documentation (CLI_MIGRATION_PLAN.md, GRADLE_MIGRATION.md)
- Remove test files and configuration files no longer needed
- Total: 134 files removed

This cleanup removes files that were generated during the build process
or are no longer relevant after the migration to Gradle and Apache Commons CLI.

Author: cm45t3r