feat(design): Warm Cinema redesign + fast-start players

Full visual overhaul from Cyber-Cinematic Glass to "Warm Cinema":
warm charcoal (#0B0908), cream (#F3E9DF), ember (#D9541F).
Fraunces (editorial serif) for display, Karla for body/UI.

Design
- app_colors: new palette, all existing token names preserved,
  plus posterScrim/heroScrim gradients and lift()/emberFocus() shadows
- app_theme: new type scale, tighter radii, 20+ component themes
- mobile_theme aligned on the same tokens
- glass_container: opaque layered surfaces replace glassmorphism;
  adds GlassCard (hover + remote-focus states) and CinemaBackdrop
- players and boot splash restyled (film-leader motif, no web fonts)

Performance
- remove every BackdropFilter (33 call sites): backdrop blur forced a
  full framebuffer read per frame per card, the main scroll jank source
- bundle Fraunces/Karla as assets: google_fonts no longer fetches from
  fonts.gstatic.com at startup
- drop the blocking hls.js CDN script from index.html; no Dart code
  ever used it, only the player iframes need it
- self-host hls.js/mpegts.js and load them on demand, so ~213 KB of
  mpegts is never downloaded for HLS streams
- bound image decode size on 10 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)
- event-driven start instead of a 200 ms buffer poll plus a 1.5 s wait
- initialLiveManifestSize 3 -> 1, liveSyncDurationCount 10 -> 2,
  startFragPrefetch on, testBandwidth off
- MPEG-TS initial stash 512 KB -> 64 KB
- adaptive escalation fast -> balanced -> safe on repeated stalls
  (60 s rolling window), applied live for HLS so there is no visible cut

Pre-existing build breakage fixed along the way
- undefined AppColors.shimmer, AppTheme.durationXs and spacing8/12/16/32
- broken relative imports in channel_card and quality_selector_widget
- missing GlassCard widget and hasBorder/showShadow parameters

Also resolves a leftover unmerged .claude/settings.local.json by
keeping the remote version.

Still broken (pre-existing, dead code, not reachable from main.dart):
recommendations_provider.dart and continue_watching_widget.dart import
a models/playlist.dart that no longer exists.

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

lib/core/widgets/components/ui_components.dart

@@ -149,7 +149,7 @@ class _GradientButtonState extends State<GradientButton>
                         ],
                         Text(
                           widget.label,
-                          style: GoogleFonts.inter(
+                          style: GoogleFonts.karla(
                             color: AppColors.onSurface,
                             fontWeight: FontWeight.w600,
                             fontSize: 14,
@@ -253,7 +253,7 @@ class LiveBadge extends StatelessWidget {
           const SizedBox(width: 4),
           Text(
             'LIVE',
-            style: GoogleFonts.inter(
+            style: GoogleFonts.karla(
               color: AppColors.onSurface,
               fontSize: 10,
               fontWeight: FontWeight.w700,
@@ -302,7 +302,7 @@ class CategoryChip extends StatelessWidget {
           ),
           child: Text(
             label,
-            style: GoogleFonts.inter(
+            style: GoogleFonts.karla(
               fontSize: 13,
               fontWeight: isSelected ? FontWeight.w600 : FontWeight.w500,
               color: isSelected ? AppColors.primary : AppColors.onSurfaceVariant,
@@ -458,7 +458,7 @@ class _MediaCardState extends State<MediaCard>
                                   const SizedBox(width: 4),
                                   Text(
                                     widget.rating!,
-                                    style: GoogleFonts.inter(
+                                    style: GoogleFonts.karla(
                                       color: AppColors.onSurface,
                                       fontSize: 10,
                                       fontWeight: FontWeight.w700,
@@ -502,7 +502,7 @@ class _MediaCardState extends State<MediaCard>
                     textAlign: TextAlign.center,
                     maxLines: 1,
                     overflow: TextOverflow.ellipsis,
-                    style: GoogleFonts.inter(
+                    style: GoogleFonts.karla(
                       color: _isHovered
                           ? AppColors.primary
                           : AppColors.onSurface,
@@ -518,7 +518,7 @@ class _MediaCardState extends State<MediaCard>
                       textAlign: TextAlign.center,
                       maxLines: 1,
                       overflow: TextOverflow.ellipsis,
-                      style: GoogleFonts.inter(
+                      style: GoogleFonts.karla(
                         color: AppColors.onSurfaceVariant,
                         fontSize: 11,
                       ),