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/DataTable.tsx

@@ -60,6 +60,7 @@ export default function DataTable<T>({
   onSortChange,
   filters: filtersProp,
   onFiltersChange,
+  fixedLayout = false,
 }: {
   rows: T[];
   columns: Column<T>[];
@@ -96,6 +97,12 @@ export default function DataTable<T>({
   // default internal, persistKey-backed filters.
   filters?: FilterMap;
   onFiltersChange?: (next: FilterMap) => void;
+  // Opt into `table-layout: fixed` (default is `auto`). In fixed mode the table width == its
+  // container at every zoom/text-size — the columns with an explicit `width` keep it, and the rest
+  // (the fluid text columns) split what remains and TRUNCATE instead of pushing the table wider than
+  // the viewport. Off by default so existing content-sized tables (playlists, discovery, Plex) are
+  // untouched; the channel manager turns it on so its row never scrolls horizontally out of view.
+  fixedLayout?: boolean;
 }) {
   const { t } = useTranslation();
   const initial = loadPersist(persistKey);
@@ -224,7 +231,17 @@ export default function DataTable<T>({
       {(controlsPosition === "top" || controlsPosition === "both") && topControls}
       {/* Wide screens: table. The wrapper isn't clipped so header filter popovers can overflow. */}
       <div className="hidden md:block">
-        <table className="w-full border-collapse text-sm">
+        <table className={`w-full border-collapse text-sm ${fixedLayout ? "table-fixed" : ""}`}>
+          {/* In fixed-layout mode a colgroup drives the column widths: those with an explicit
+              `width` keep it, and the unspecified (fluid) columns split the remainder — so the
+              table never exceeds its container and the fluid cells truncate instead. */}
+          {fixedLayout && (
+            <colgroup>
+              {columns.map((col) => (
+                <col key={col.key} style={col.width ? { width: col.width } : undefined} />
+              ))}
+            </colgroup>
+          )}
           <ColumnHead
             columns={columns}
             sort={sort}