fix(sensing-server): align vital sign tolerance with empty holdout threshold (#2169)

[VaibhavvPant]

Closes #2169

Summary

• Defined BOOTSTRAP_VALIDATION_MAX_VITALS (2 of 12) in bootstrap_baseline.rs to align with the documented 10/12 empty room tolerance requirement.
• Updated evaluate_validation to permit intermittent/spurious vital sign noise within tolerance rather than unconditionally failing.
• Updated the promote route handler in main.rs to report informative failure messages when vital sign noise exceeds the threshold.
• Updated unit tests in bootstrap_baseline.rs to verify the tolerance threshold and ensure excessive vitals/stale frames still fail closed.