feat(channels): R14 zoom-fit table — fluid columns + column fogyókúra

- DataTable: opt-in `fixedLayout` (colgroup + table-layout:fixed) so the
  table fits its container at any zoom/text-size; only the channel manager
  opts in — playlists/discovery/Plex keep auto-sizing.
- Remove the N/S/L and Sync columns from the manager table. Fully-synced
  status becomes a ✓ charm on the Stored count; the sync filter moves to an
  `applySyncFilter` pre-filter still driven by the top chips.
- Channel column is now fluid: ChannelLink truncates with the full name on
  hover (title). Data columns get fixed widths so only Channel/About flex.
- N/S/L (normal/short/live) breakdown moves to the channel page: add the
  three counts to the channelDetail endpoint (one grouped query, same
  filters as the list) + the ChannelDetail type + a meta-line entry.
- Drop the now-dead sync/types i18n keys (en+hu).

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

@@ -12,6 +12,7 @@
   "videoCount_other": "{{count}} videos",
   "videoCountStored": "{{stored}} / {{total}} videos",
   "totalViews": "{{formatted}} views",
+  "videoTypes": "{{normal}} normal / {{short}} shorts / {{live}} live",
   "joined": "Joined {{date}}",
   "loadingVideos": "Loading this channel's videos…",
   "tabVideos": "Videos",