MonitorService IllegalStateException Fix-created-by-agentic

[doppleware]

The MonitorService is throwing IllegalStateException with "monitor failure" message. This issue was introduced in PR #17.

Root cause:

• Intentional exception throwing in monitor() method
• Incorrect isRunning() implementation
• Missing state validation

Fix:
PR #79 addresses these issues by:

1. Fixing isRunning() to return actual state
2. Adding proper state validation
3. Adding logging
4. Removing intentional exception throwing

Related incident: b2f3824a-3655-11f0-bc70-ca59c7e8e81d