fix(ui): make the workspace usable on phone-sized screens

The shell was half-adapted below 640px: the rail flipped to a horizontal
bar but the link lists inside it kept stacking downwards, so the navigation
was drawn outside the bar and over the header (#1100).

Three resizable rails — the shell context panel, the live-layout channel
sidebar and the M3U channel drawer — kept their persisted desktop width,
which left the content around 50px on a 375px screen. They now span the
full width and stack above the content. The inline width written by
ResizableDirective is why these rules need `!important`.

Found while walking the rest of the UI at 375px and 768px:

- The detail hero kept poster and details side by side, squeezing the
  action row below its own labels until "Play" was clipped to its icon.
- The settings section list did not scroll and painted over the footer,
  which also affected short desktop windows.
- Hiding the M3U channel list on a phone was one-way: the restore handle
  was hidden and only Cmd/Ctrl+B could bring it back.
- The live header drew the channel count and the paginator on top of each
  other up to tablet width, because the paginator does not shrink and the
  meta collapsed to zero width and overflowed its box.
- The search scope checkbox was pushed off the right edge.

Live TV states a floor for the player instead of a ceiling for the lists,
so the video keeps a usable share of the screen under the categories panel
and the channel list.

Closes #1100

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

libs/ui/components/src/lib/content-hero/content-hero.component.scss

@@ -534,6 +534,26 @@
     }
 }
 
+// A phone cannot carry the poster and the details side by side: the details
+// column drops to ~200px, and the action buttons are then squeezed below
+// their own labels ("Play" clipped down to its icon). Stack them instead.
+@media (max-width: 640px) {
+    .hero__content {
+        flex-direction: column;
+        align-items: stretch;
+        padding-inline: 16px;
+    }
+
+    .poster {
+        width: 140px;
+        align-self: center;
+    }
+
+    .details__title {
+        text-align: center;
+    }
+}
+
 // ============================================================================
 // Animations
 // ============================================================================