feat: tag chips count their channels, Plex shows a file's size, a skip waits, Continue watching opens whole

The channel manager's tag chips carry a muted count. A Plex item's Info page names the file's size.
An auto-skip's countdown starts 3 s into the marker, with its button there from the start and a delay of
0 still immediate. Continue watching has a See all, opening Browse on in progress, last watched first;
Recently added's sets the watch state back so it opens what it says.

frontend/src/modules/plex/PlexInfo.tsx

@@ -4,7 +4,7 @@ import { useTranslation } from "react-i18next";
 import { useQueryClient } from "@tanstack/react-query";
 import { Check, ExternalLink, FolderPlus, ListPlus, Play, RotateCcw, Star, X } from "lucide-react";
 import { api, type PlexCard, type PlexFilters, type PlexItemDetail } from "../../lib/api";
-import { formatCompact, formatDecimal, formatRuntime } from "../../lib/format";
+import { formatBytes, formatCompact, formatDecimal, formatRuntime } from "../../lib/format";
 import { notifyActionError } from "../../lib/actionErrors";
 import { DetailCustomizeMenu, Filterable, PrefToggle } from "./plexDetailUi";
 import { DetailAside, DetailAsideToggles, DetailKeywords } from "./plexDetailAside";
@@ -452,6 +452,9 @@ export default function PlexInfo({
                   {detail.duration_seconds ? (
                     <span className={mutedCls}>{formatRuntime(detail.duration_seconds, lang)}</span>
                   ) : null}
+                  {detail.size_bytes ? (
+                    <span className={mutedCls}>{formatBytes(detail.size_bytes, lang)}</span>
+                  ) : null}
                   {detail.studio && (
                     <Filterable
                       tag