m/paliad#61 Slice C frontend pass.
Discovery (Geteilte Vorlagen):
- New 4th tab on /checklists between "Meine Vorlagen" and "Vorhandene
Instanzen". Filters the merged catalog response to authored entries
not owned by the caller (firm-visible OR globally-promoted OR
share-recipient). Tab state round-trips via ?tab=gallery.
- Regime filter pills (UPC / DE / EPA / OTHER) operate independently
from the main Vorlagen tab.
- Cards show regime badge, item count, author line, visibility chip.
- Self-filter relies on /api/me email match — loadMe() fires once on
page boot and is idempotent.
Versioning UI on /checklists/instances/{id}:
- "Vorlage aktualisiert" badge appears when the instance's
template_version is known AND lags the live template version (only
for authored templates; static templates never bump). Shows "v{from}
→ v{to}" delta.
- "Änderungen anzeigen" button opens a diff modal that compares the
instance's template_snapshot against the live template body.
Item-level grouping by (section title, item label). Surfaces added /
removed / changed items with localised section labels. Empty state
when only metadata changed.
i18n: 13 new keys per language (DE + EN) under
checklisten.tab.gallery, checklisten.gallery.*, checklisten.filter.other,
and checklisten.instance.{outdated,diff}.*. Total 2666 keys.
Build hygiene: bun run build clean; i18n scan clean. Go build/vet/test
+ TestBootSmoke ./cmd/server/ all green.