Fix M2: clamp picksplit nBins to nTuples to prevent out-of-bounds
read on the entries array when called with a single tuple.
Fix H2: use WGS72_AE as effective bin_low for the first bin in L0
inner_consistent, preventing false negatives when objects with lower
SMA than the first label are inserted after index creation.
Fix H3: reject degenerate TLEs (mean_motion <= 0) early in the
visibility filter rather than propagating nonsensical values.
Fix L1: extract shared tle_passes_visibility_filter() to eliminate
duplicated 3-stage filter logic between leaf_consistent and the
standalone tle_visibility_possible operator.
Add boundary tests: degenerate TLE, polar observer, zero-duration
window, and post-insert index-vs-seqscan consistency check.
2-level SP-GiST index on TLE data: SMA at L0, inclination at L1, with
query-time RAAN filter via J2 secular precession. New &? operator
(observer_window &? tle) returns true when a satellite might be visible
from a ground observer during a time window.
Index prunes by altitude band, inclination+footprint vs observer
latitude, and RAAN alignment against local sidereal time. Operator
class tle_spgist_ops is opt-in (not default), coexists with existing
GiST tle_ops. Equal-population picksplit with sqrt(n) bins.
