test(notification): Write notification tools test suite

[coderooz]

Summary

Write comprehensive tests for the enhanced notification tools.

Acceptance Criteria

• Create \ ests/notification-tools-test.js\ using
  ode:test\ runner
• Test notify_user: urgency validation, sound selection, repeat calculation
• Test notify_user: custom sound path validation
• Test notify_user: history storage
• Test get_notification_history: filtering by urgency, date range
• Test edge cases: invalid urgency, missing message, repeat bounds
• Test dry run mode
• Follow existing test patterns (see \ ests/feedback-system-test.js)

Test Data

• Valid urgency levels: info, warning, critical
• Invalid urgency: 'unknown', '', null
• Sound paths: valid path, non-existent path, path traversal attempt
• Repeat values: 0, 1, 5, 6, -1

Related

• Milestone: v2.6.0 — Audio Notification System
• Depends on: 💡 Feature Ideas & Roadmap Suggestions #3 (notification registration)