refactor(ui): remove dead portal code and share detail styles

docs/architecture/iptvnator-ui-guidelines.md

@@ -38,6 +38,8 @@ Use it when changing existing views or introducing new list-based UI in the work
   `apps/web/src/m3-theme.scss`
 - Settings surfaces:
   `apps/web/src/app/settings/settings.component.scss`
+- Detail view shell styles:
+  `libs/ui/styles/_detail-view.scss`
 
 ## Shared Tokens
 
@@ -84,6 +86,17 @@ Use this pattern for:
 
 Do not add extra badges, left rails, or second selection systems unless there is a strong reason.
 
+## Detail Views
+
+VOD and series detail screens share the `detail-view` Sass mixin from
+`libs/ui/styles/_detail-view.scss`. Feature-local `styles/detail-view.scss`
+files should only import that mixin and pass small typography overrides when a
+provider needs them.
+
+Do not copy the full detail-view stylesheet into feature libraries. Add shared
+layout changes to the mixin, and keep provider-specific differences explicit in
+the wrapper file that includes it.
+
 ## Channel List Item
 
 The shared row should be reused instead of rebuilding channel markup per view.