Replace the two-option `ListSort` enum with an orthogonal sort field
(created/updated/title/author, default updated) and direction
(asc/desc, default desc). The catalog now defaults to last-updated-first
and lets the user order by any field in either direction.
Backend builds ORDER BY from the enums only (no injection seam), with a
NULLS-LAST author subquery and a stable id tie-break. Frontend adds a
direction toggle with per-field defaults (dates desc, text asc) and
labels (Newest/Oldest vs A->Z/Z->A), reusing SegmentedControl; URL state
omits the per-field defaults and validates on hydrate.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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