Update category header and list views to provide clearer context
and improve navigation state handling.
- Display category name with current page/total pages when viewing a
category (non-detail) so users see which page they're on.
- Add i18n "PAGE" key and fill "SELECT_CATEGORY" in translations for
en/de/ru to support the new page label and existing messaging.
- Tidy live-stream layout template formatting and fix filter pipe
spacing for consistency.
- Change no-channel-selected fallback to use the translated
"PORTALS.SELECT_CATEGORY" string.
- Preserve category selection state on CategoryContentView init:
only set selected category when the route category differs from
the current selection to keep paging/scroll position when returning
from a detail view.
These changes improve UX by making pagination explicit and avoiding
unnecessary state resets when navigating between list and detail.
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