fix(popup): polish custom-server, host-control card & co-host UX

- Manual Connect: split the server picker into its own inset panel,
  visually separated from the Room ID / Password fields (they were
  welded together in one flat list).
- Custom server URL: stop auto-prepending ws:// — default to wss://
  for real hosts, ws:// only for localhost/127.0.0.1 (matches what
  the background already enforces; the displayed URL no longer lies).
- Host Control card: replace the raw native checkbox with the proper
  .toggle-switch slider used in Options; move the toggle row from a
  <label> to a <div> to avoid an illegally nested label.
- Co-host discoverability: owner-only hint in the Host Control card
  pointing to the participant list (new NOTICE_COHOST_HINT across all
  15 locales). Shown only when actionable: owner + co-host-capable
  relay + host-only active.
- Peer row: group right-side badges/actions into one container so they
  no longer scatter via space-between or collide with long names;
  restyle the give/revoke button (padding, weight, hover fill, tooltip).
- Gate promote/demote (and role badges) on host-only mode being ON,
  in addition to the existing owner-privilege check — roles are moot
  in 'everyone' mode, so no badge/button noise there.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

extension/locales/tr.json

@@ -48,6 +48,7 @@
   "LABEL_HOST_CONTROL_TOOLTIP": "Bu odada oynatmayı kimin kontrol edebileceğini belirleyin",
   "LABEL_HOST_ONLY_TOGGLE": "Oynatmayı yalnızca ben kontrol edebilirim",
   "NOTICE_HOST_CONTROLS": "Oynatmayı herkes için sunucu kontrol eder.",
+  "NOTICE_COHOST_HINT": "İpucu: aşağıdaki katılımcı listesinde tek tek katılımcılara kontrol verin.",
   "BADGE_HOST": "Sunucu",
   "BADGE_GUEST": "Misafir",
   "BADGE_CONTROLLER": "Kontrolcü",