[jubarauna]

Summary

Add Cruise.follow_track(lat, lon, tolerance_m=1000) for optimizing cruise altitude and speed along a recorded ground track. Boundary nodes lie on an arc-length-parametrized cubic spline; interior collocation and quarter-interval samples stay within the requested tolerance. Progress is ordered from the origin to the destination.

Unlike node-only constraints, the interior checks also restrict excursions between boundary nodes. This remains a sampled numerical constraint, not a continuous-path guarantee. The default tolerance is 1 km; tighter tolerances and sharper bends can require more mesh intervals.

Behavior

• Validate matching finite 1D coordinate arrays, at least four points, valid latitude/longitude ranges, and no consecutive duplicates.
• Require endpoints within 1 km of the flight endpoints and snap them to the exact flight boundaries without modifying the input arrays.
• Preserve turn-rate limits and reject combining a prescribed track with fix_track_angle().
• Include the reference curve in spatial bounds, seed the trajectory and heading along it, and use its length for the flight-duration seed.
• Rebuild projected splines for each formulation, including the shared projection used by MultiAircraft.
• Support fixed Mach, grid objectives, and wind under the existing single-aircraft/fleet restrictions. Keep the original behavior when no track is configured.

The branch includes current main, including PRs #34 and #32.

Validation

• 33 track tests pass: input validation, endpoint snapping, projection changes, detour bounds, dense trajectory checks, turn-rate checks, fixed Mach with exact grid costs, wind, and fleet solving.
• On the bowed-track regression, a 1 km tolerance converges with 20 intervals; a 100 m tolerance converges with 40 intervals. Dense verification samples stay within tolerance plus the approximately 2 m reference-sampling resolution.
• Ruff lint and formatting pass. Type checking passes for the changed implementation and tests.
• All 94 targeted cruise, track, fleet, continuous-control, grid, waypoint, and wind regression tests pass (pytest ... -n auto). Full GitHub CI is running on the updated branch.