feat(design): Warm Cinema theme + event-driven adaptive players

Replaces the Projector Noir palette with "Warm Cinema" and rebuilds the
web players around a shared, event-driven engine.

Design
- app_colors: warm charcoal (#0B0908), cream (#F3E9DF), ember (#D9541F);
  adds posterScrim/heroScrim gradients, lift()/emberFocus() shadows,
  const cream-alpha tokens replacing Colors.whiteNN, and primaryFill,
  a deeper ember reserved for text-bearing fills so white labels clear
  the 4.5:1 AA threshold that #D9541F alone does not
- app_theme / mobile_theme: Fraunces (display serif) + Karla (body),
  tighter radii, 20+ component themes
- glass_container: opaque layered surfaces replace the blurred glass
- themed_loading_screen restyled; players and boot splash follow

Performance
- drop every BackdropFilter: backdrop blur forced a full framebuffer
  read per frame per card, the main source of scroll jank
- bundle Fraunces/Karla as assets so google_fonts stops fetching from
  fonts.gstatic.com at startup
- bound image decode size on 12 sites: a 40-poster grid drops from
  ~240 MB to a few tens of MB of GPU memory

Players (new shared engine: web/xf-player-core.js)
- start on media events instead of polling the buffer every 100-200 ms
- hls.js/mpegts.js loaded on demand, so ~213 KB of mpegts is never
  fetched for HLS streams
- liveSyncDurationCount 10 -> 2, startFragPrefetch on, testBandwidth
  off, MPEG-TS initial stash 512 KB -> 64 KB
- adaptive escalation fast -> balanced -> safe after repeated stalls in
  a 60 s window, applied live for HLS so there is no visible cut

Preserved from the recent streaming work on main: server-side quality
selection, stable player viewId, the turbo direct MPEG-TS path, vendored
library cache headers and the CI/Docker changes. Only the theme layer and
the player front-end were replaced; GlassCard stays in ui_components.

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

lib/core/widgets/hero_carousel.dart

@@ -179,6 +179,7 @@ class _HeroCarouselState extends State<HeroCarousel>
           Image.network(
             item.imageUrl!,
             fit: BoxFit.cover,
+            cacheWidth: 1280,
             errorBuilder: (context, error, stackTrace) {
               return Container(
                 color: AppColors.surface,
@@ -220,7 +221,7 @@ class _HeroCarouselState extends State<HeroCarousel>
             ),
             child: Text(
               item.badge!,
-              style: GoogleFonts.instrumentSans(
+              style: GoogleFonts.karla(
                 fontSize: 12,
                 fontWeight: FontWeight.w700,
                 color: AppColors.primary,
@@ -233,7 +234,7 @@ class _HeroCarouselState extends State<HeroCarousel>
           item.title,
           maxLines: 2,
           overflow: TextOverflow.ellipsis,
-          style: GoogleFonts.syne(
+          style: GoogleFonts.fraunces(
             fontSize: 48,
             fontWeight: FontWeight.w800,
             color: AppColors.textPrimary,
@@ -247,7 +248,7 @@ class _HeroCarouselState extends State<HeroCarousel>
             item.subtitle!,
             maxLines: 2,
             overflow: TextOverflow.ellipsis,
-            style: GoogleFonts.instrumentSans(
+            style: GoogleFonts.karla(
               fontSize: 16,
               fontWeight: FontWeight.w400,
               color: AppColors.textSecondary,
@@ -292,7 +293,7 @@ class _HeroCarouselState extends State<HeroCarousel>
                           const SizedBox(width: 8),
                           Text(
                             'Play',
-                            style: GoogleFonts.instrumentSans(
+                            style: GoogleFonts.karla(
                               fontSize: 16,
                               fontWeight: FontWeight.w700,
                               color: AppColors.primary,
@@ -330,7 +331,7 @@ class _HeroCarouselState extends State<HeroCarousel>
                         const SizedBox(width: 8),
                         Text(
                           'More Info',
-                          style: GoogleFonts.instrumentSans(
+                          style: GoogleFonts.karla(
                             fontSize: 16,
                             fontWeight: FontWeight.w700,
                             color: AppColors.textPrimary,