feat: add company namer with domain checks

[arnabnandy7]

Summary

Adds a Java company-naming example that generates company name suggestions and checks their matching .com domains.

Closes #46.

Changes

• Add an annotation-driven CompanyNamer workflow.
• Generate structured company names, domains, and rationales.
• Check domains using the JDK DNS resolver without requiring another API key or consuming a provider quota.
• Normalize and validate proposed domain names.
• Cache DNS results during the application lifecycle.
• Distinguish between:
  • IN_USE when DNS records exist.
  • POTENTIALLY_AVAILABLE when no DNS records are found.
  • UNKNOWN when validation or lookup fails.
• Document that potentially available domains must still be confirmed with a registrar.
• Add usage and implementation documentation to the root and Java READMEs.
• Add focused unit tests with deterministic DNS resolver stubs.

Testing

Tests run: 6, Failures: 0, Errors: 0, Skipped: 0
BUILD SUCCESS

Command:

./mvnw -pl examples-java -am \
  -Dtest=CompanyNamerTest,DomainAvailabilityServiceTest \
  -Dsurefire.failIfNoSpecifiedTests=false \
  test

[arnabnandy7]

@johnsonr @igordayen although it's a very old issue, still raising this. If needed please review.