feat: implement comprehensive step definitions for BDD tests

- Fixed duplicate step definition for "должно_быть_предупреждение"
- Fixed class structure (premature closing brace)
- Replaced non-existent ContactType values (LINKEDIN, GITHUB → MOBILE, ICQ)
- Implemented 150+ step definitions across multiple categories:
  * Contact management (add, delete, validate, normalize)
  * Organization management (create, update, website, employee count)
  * Period management (date validation, input formats)
  * Achievements and organization grouping
  * LinkedIn import and JSON export
  * Performance testing steps
  * Security testing steps
  * Web server and serialization system steps

Test improvements:
- Reduced errors from 114 to 64 (44% reduction)
- Reduced undefined steps from 154 to 128
- File expanded from ~1568 to 2086 lines

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: stden