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/components/ChannelLink.tsx

@@ -41,12 +41,16 @@ export default function ChannelLink({
           onMouseDown={(e) => {
             if (e.button === 1) e.preventDefault(); // suppress middle-click autoscroll
           }}
+          // title = the full name, so a truncated fluid-column name is still readable on hover.
+          title={name}
           className="text-sm font-medium truncate hover:text-accent text-left min-w-0"
         >
           {name}
         </button>
       ) : (
-        <span className="text-sm font-medium truncate min-w-0">{name}</span>
+        <span title={name} className="text-sm font-medium truncate min-w-0">
+          {name}
+        </span>
       )}
       <Tooltip hint={t("channels.row.openOnYouTube")}>
         <a