- IOD bootstrap: Gauss/Gibbs/double-r methods to generate
 initial TLE from angles-only (eliminates seed requirement)
 - Covariance output: Return (A^TWA)^{-1} matrix for
 uncertainty estimates / conjunction screening
 - Multi-observer: Accept observations from multiple ground
 stations
 - Adaptive step limiting: Dynamically tune correction limits
 per Vallado's observation about different strategies failing
 on different satellite subsets