Implements issue #130 with:
- Basic utilities: distance, angle_between, normalize_angle, lerp, clamp
- Grid algorithms: bresenham_circle, bresenham_line, filled_circle
- OrbitalBody class with recursive positioning (star -> planet -> moon)
- OrbitingShip class for relative ship positioning on orbit rings
- Pathfinding helpers: nearest_orbit_entry, optimal_exit_heading,
is_viable_waypoint, line_of_sight_blocked
- Comprehensive test suite (25+ tests)
Designed for Pinships turn-based space roguelike with:
- Discrete time steps (planets move in whole grid squares)
- Deterministic position projection
- Free orbital movement while in orbit
- Support for nested orbits (moons of moons)
closes#130🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
