feat(design): the download, notification and Scheduler action lists (C1) — the rows' "…", the band's and the strip's "…" (E28 S3e3)

A download row keeps play (pause / resume / retry in the queue) and the save link; the editors,
sharing, re-download, the copies and cancel / delete / remove moved into its "…"
(useDownloadActions). A link inside the row keeps the browser's own right-click menu. A
notification row keeps its link and its unread mark and shows its dismiss on hover; an activity
notice's Find in feed and Undo are in its "…". The inbox band keeps Mark all read and puts Clear
everything, now behind a confirm, in its "…". The Scheduler strip keeps Run all and Pause and puts
Purge discovery in its "…". Polled lists key their menus by id (keyOf). ui/menuGroups draws a
rule only between two non-empty groups. Find in feed also drops the tag, search and age filters
that could hide the video it looks for.

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

@@ -3,8 +3,12 @@
   "empty": "Nincs új értesítés.",
   "markAllRead": "Összes olvasott",
   "clearAll": "Összes törlése",
+  "clearConfirmTitle": "Törlöd az összes értesítést?",
+  "clearConfirmBody": "Minden itteni értesítés eltűnik a listából, olvasott és olvasatlan is. Nem hozhatók vissza.",
   "markRead": "Olvasottnak jelöl",
   "dismiss": "Elvetés",
+  "rowMenu": "Értesítés műveletei",
+  "menu": "Értesítésközpont műveletei",
   "sectionSystem": "Rendszer",
   "sectionActivity": "Tevékenység",
   "andMore": "és még {{count}}",