MS-238/feat: Add SafeObjectParser utility to prevent StackOverflowError in logging

Summary

Introduces SafeObjectParser utility to safely convert objects to string representation, preventing StackOverflowError caused by circular references in JPA entities (Order/OrderLine bidirectional relationship).

Changes

• Added SafeObjectParser utility class with circular reference detection and max depth limit (50)
• Added @ToString annotation to DTOs missing it for consistent logging
• Added comprehensive unit tests covering null values, collections, maps, circular references, and deeply nested objects

Closes MS-238