test: Add tests for untested management scripts

[db-tycoon-stephen]

Problem

35+ scripts have zero test coverage. The most critical untested scripts are the core management commands users actually run.

Priority Scripts to Test

1. manage_warehouses.py - Warehouse operations
2. cost_optimization.py - Cost analysis
3. security_audit.py - Security checks
4. backup_restore.py - Backup/restore operations
5. deploy_safe.py - Safe deployment wrapper
6. monitor_audit.py - Audit trail
7. monitor_metrics.py - Operational metrics

Approach

Use mocked Snowflake connections (similar to existing test patterns). Focus on:

• CLI argument parsing
• Output formatting
• Error handling paths
• Edge cases

Acceptance Criteria

• Tests for all 7 priority scripts
• All tests pass without Snowflake connection
• Coverage for these scripts > 70%