Fix false positive on tall displays (relative threshold)

[EmpireOperating]

Fixes #33.

Summary:

• Adds a relative threshold (10% of outer dimension) on top of the existing absolute threshold (170px) to avoid false positives on large/tall displays.
• Adds node:test regression tests for a 1920×1980-style scenario.
• Exports a small evaluateDevtools(...) helper for testability.

Notes:

• I couldn't reproduce on real hardware; this is a conservative heuristic mitigation based on the reported window-metric pattern.