fix(live-tv): honour Cmd/Ctrl+B on collection pages and hide the header rail toggle on phones

Codex review follow-ups on #1555:

- The hidden-list state advertises Cmd/Ctrl+B, but the favorites/recent
  collection page had no handler; only the routed M3U/Xtream/Stalker live
  layouts did. The page now toggles the collection surface while its live
  tab is on screen, with the same typing/inert guards as the other hosts.
- At the phone breakpoint the header already holds the drawer toggle,
  switcher, search and Add; the live rail is a bottom drawer with its own
  toggle there, so the header rail toggle is hidden below 640px.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/architecture/iptvnator-ui-guidelines.md

@@ -310,6 +310,8 @@ remain local when the meaning is explicit.
   exception that deserves the cue. Collection pages are deliberately excluded:
   only the page knows whether its live tab, and therefore the rail, is on
   screen, so its own header toggle beside the content switch stays the owner.
+  At the phone breakpoint (≤640px) the header toggle is hidden: the rail is a
+  bottom drawer there with its own toggle and the header has no spare width.
 - While the rail is collapsed and nothing is playing, every live host renders
   `app-channel-list-hidden-state` (`@iptvnator/portal/shared/ui`) instead of
   the "select a channel" empty state: a title that says the list is hidden, a