chore: remove deprecated .cursorrules file [skip-sync]

- Removed obsolete .cursorrules file
- Migration to .cursor/rules/*.mdc structure is complete
- All rules now properly organized with smart context attachment

Cleanup completes the Cursor IDE migration to modern rules system.

[skip-sync]

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

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

Author: niksacdev