Shared Angle Solver

Zero-finding at build time and adjustment-solving at inverse time are the same mathematical problem: find the launch angle whose trajectory meets the target. So lob solves both with one shared routine.

Sharing guarantees the zero a rifle is zeroed with and the adjustments that assume that zero are computed with identical tolerance, bounds, and jump handling; two implementations could drift subtly apart. It also halves maintenance: a fix to convergence behavior applies to both features at once, with a smaller diff than guarding every caller. See Shared Angle Solver for the dedicated treatment, and Drag for how the curves it flies were built.