Refuse header-ephemeris photometry on sidereally tracked frames.

[sfoale]

What

EphemerisHeaders now refuses frames with fits header keyword SRCTYPE = EXTRASOLAR, before any
pixels are read, and names the operation that can measure them instead.

Why

SRCTYPE records how the observation was scheduled, and so how the mount tracked.
On a solar-system object the scheduler follows an ephemeris and CAT-RA/CAT-DEC
carries the target's own position; on EXTRASOLAR those coordinates record where the telescope
was pointed.

Testing

Two tests added: EXTRASOLAR frames are refused, MINORPLANET frames still produce
a light curve. Full suite passes. Verified end to end on real data — the 3I/ATLAS rp
frames are refused, Kleopatra still returns 13 rows.

[capetillo]

Nice catch! LGTM