fix(ui): E31 S2 — the tab names the object, the channel header wraps, the player fits a short window

- The browser tab names the place and the object: PageHeading reports the
  view's own title (lib/documentTitle), so a channel, playlist or any Plex
  view reads "<object> · <module> · Siftlode" however it was opened; the
  Feed is named too; a season adds its show (tabTitle).
- The channel page's tab + action row wraps and lets the tag lane fold into
  "+N": at 1024 it ran past the edge and the page scrolled sideways.
- The YouTube player card's width is capped from the window height less the
  chrome measured under the video: at 133% zoom (685px) it cut its channel row.
- Plex certificate words (Not Rated, Approved, Passed) are named through the
  vocabulary on the info badge, show page, collection, filter and chips.
- DESIGN.md: the zoom target is 125% and 133%, not 200% (decision log).

frontend/src/components/ui/Headings.tsx

@@ -1,4 +1,5 @@
-import type { ComponentPropsWithoutRef, ReactNode } from "react";
+import { type ComponentPropsWithoutRef, type ReactNode, useRef } from "react";
+import { useNameTabAfter } from "../../lib/documentTitle";
 import { useOwnPageHeading } from "./pageHeading";
 
 // The page's heading outline (B4, UX-15): one `h1` per page, then a heading per section. A screen
@@ -6,10 +7,16 @@ import { useOwnPageHeading } from "./pageHeading";
 // structure from exactly the people who navigate by it.
 
 /** A view's own visible title (a channel, a Plex show, a playlist): the page's `h1`, in place of the
- *  shell's hidden page name. */
-export function PageHeading(props: ComponentPropsWithoutRef<"h1">) {
+ *  shell's hidden page name, and the object the browser tab names (`lib/documentTitle`). `tabTitle`
+ *  only when the heading alone does not say what it is (a season: "Season 1" → "Voyager · Season 1"). */
+export function PageHeading({
+  tabTitle,
+  ...props
+}: ComponentPropsWithoutRef<"h1"> & { tabTitle?: string }) {
   useOwnPageHeading();
-  return <h1 {...props} />;
+  const ref = useRef<HTMLHeadingElement>(null);
+  useNameTabAfter(ref, tabTitle);
+  return <h1 ref={ref} {...props} />;
 }
 
 /** A section's caption: the small uppercase muted label, as a heading. `level` 3 inside a dialog or