The Live Slideshow already covers the core of #202 (fullscreen kiosk,
live-appending new uploads, timing/transitions/watermark, per-event
opt-in via the share link). This adds the two customization dimensions
the reporter also asked for:
- **Play order** (show_order): 'chronological' (upload order, default) or
'random' — the client shuffles the initial set (Fisher-Yates) so
live-appended uploads keep working.
- **Category filter** (show_category_id): restrict the slideshow to a
single photo category (NULL = all photos, default). Enforced
server-side on the slideshow /photos access and mirrored in the
/session + /state photo_count, so the kiosk viewer can't widen the set.
Per-event enable/disable (default off) is unchanged — it's the existing
'Generate/Disable slideshow link' flow (no token = no slideshow).
- Migration 158: show_order (default 'chronological') + show_category_id.
- Admin: Play-order dropdown + category picker in the Live Slideshow card
(picker hidden for events without categories); EN + DE i18n.
- Verified: migration (SQLite + PG); live API (category filter → 3/2/5
photos + matching count; order propagates) and the running kiosk
requests exactly the filtered set; tsc clean, 136 backend tests pass.