Task 426: Add Tests for Untested orbital.ts Functions

Status: DONE

Summary

orbital.ts exports 8 functions but only 2 have tests (visViva, hohmannTransferDv). Add tests for the remaining 6 functions: escapeVelocity, circularVelocity, hyperbolicExcess, orbitalPeriod, brachistochroneAccel, brachistochroneDeltaV. All are pure math with well-known reference values.

Rationale

• Core orbital mechanics module used throughout the project
• 75% of exports lack tests
• All functions have known reference values from NASA/textbooks for validation