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/i18n/locales/en/vocab.json

@@ -165,5 +165,11 @@
     "mono": "Mono",
     "audioN": "Audio {{n}}",
     "subtitleN": "Subtitle {{n}}"
+  },
+  "certificate": {
+    "NotRated": "Not Rated",
+    "Unrated": "Unrated",
+    "Approved": "Approved",
+    "Passed": "Passed"
   }
 }

frontend/src/i18n/locales/hu/vocab.json

@@ -165,5 +165,11 @@
     "mono": "monó",
     "audioN": "{{n}}. hangsáv",
     "subtitleN": "{{n}}. felirat"
+  },
+  "certificate": {
+    "NotRated": "Nincs besorolva",
+    "Unrated": "Besorolatlan",
+    "Approved": "Jóváhagyva",
+    "Passed": "Engedélyezve"
   }
 }