Polish mobile layouts, extract ExpandableText, fix image sizing

- Stack title-hero poster/metadata vertically on mobile (flex-col md:flex-row),
  switch backdrop tall breakpoint from sm to md
- Extract bio expand/collapse logic into reusable ExpandableText component;
  use it in PersonHero and TitleHero
- Fix ContinueWatchingCard image to use fill + sizes instead of fixed
  width/height to avoid layout shift
- Add fade-out gradient on genre chip scrollbar edge on mobile
- Show scaled-down ambient glow on mobile instead of hiding it entirely
- Humanize knownForDepartment labels (Acting→Actor, Directing→Director, etc.)
- Change cast member name from truncate to line-clamp-2 for wrapping
- Hide tooltip arrow via [&>:last-child]:hidden instead of color-matching it
- Apply safe-area-inset padding to HeroBanner content on notched devices

app/(pages)/dashboard/_components/welcome-header.tsx

@@ -1,10 +1,10 @@
 export function WelcomeHeader({ name }: { name?: string | null }) {
   return (
     <div>
-      <h1 className="font-display text-3xl tracking-tight text-balance">
+      <h1 className="text-balance font-display text-3xl tracking-tight">
         Welcome back{name ? `, ${name}` : ""}
       </h1>
-      <p className="mt-1 text-sm text-muted-foreground">
+      <p className="mt-1 text-muted-foreground text-sm">
         Here&apos;s what&apos;s happening with your library
       </p>
     </div>