[choidanny719]

Several monitor behaviors lacked regression coverage, particularly configuration changes during running checks and failures while saving or pruning history.

Adds tests for:

• Primitive JSON comparisons, response-time boundaries, public IP literals, cancellation, split UTF-8 responses and interrupted connections.
• Repeated outages, configuration revisions, cancellation, deletion and transaction rollback during recovery, editing and retention.
• Manual checks on paused monitors, duplicate and capacity responses, edits during checks, retry timing and error handling.

Changes are split into three commits and touch only five test files. Application behavior, README, dependencies and CI configuration are unchanged.

Validation: 89 tests pass, up from 44; npm run demo passes. Node's coverage report shows 100% source line coverage and 97.72% branch coverage. These measurements do not imply every possible input or execution order is covered.