feat(card): show LIVE/upcoming badge where duration is absent

Live streams and upcoming/premiere videos have no fixed duration, so the
playlist row and video card left a blank where the runtime usually sits.
Show a LIVE (red) or upcoming badge instead, so it's clear the missing
time is by design, not a sync gap.

frontend/src/i18n/locales/de/card.json

@@ -1,4 +1,6 @@
 {
+  "live": "live",
+  "upcoming": "demnächst",
   "watchedUnmark": "Angesehen — zum Aufheben klicken",
   "markWatched": "Als angesehen markieren",
   "savedRemove": "Gespeichert — zum Entfernen klicken",

frontend/src/i18n/locales/en/card.json

@@ -1,4 +1,6 @@
 {
+  "live": "live",
+  "upcoming": "upcoming",
   "watchedUnmark": "Watched — click to unmark",
   "markWatched": "Mark watched",
   "savedRemove": "Saved — click to remove",

frontend/src/i18n/locales/hu/card.json

@@ -1,4 +1,6 @@
 {
+  "live": "élő",
+  "upcoming": "hamarosan",
   "watchedUnmark": "Megnézve — kattints a visszavonáshoz",
   "markWatched": "Megnézettnek jelöl",
   "savedRemove": "Mentve — kattints az eltávolításhoz",