Reverses the earlier "no colors to the device" decision now that the
echo machinery makes it safe: GetMetadata maps the stored web hex to
KOReader's fixed color names (#ce93d8→purple, #90caf9→blue,
#a5d6a7→green, #ffd54f→yellow; pink maps to purple as the closest —
round-trip drift is prevented on the device by echo suppression, and
a device edit still wins). mapColorToKOReader restored for serving;
ingest (name→hex, preserve-on-echo) unchanged.
john-okeefe
178fb2eb37