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/mobile/features/auth/screens/mobile_login_screen.dart

@@ -124,7 +124,7 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
                       const SizedBox(height: 24),
                       Text(
                         'XtremFlow',
-                        style: GoogleFonts.spaceGrotesk(
+                        style: GoogleFonts.fraunces(
                           fontSize: 32,
                           fontWeight: FontWeight.w700,
                           color: AppColors.onSurface,
@@ -133,7 +133,7 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
                       ),
                        Text(
                         'Mobile Edition',
-                        style: GoogleFonts.inter(
+                        style: GoogleFonts.karla(
                           fontSize: 14,
                           color: AppColors.onSurfaceVariant,
                           letterSpacing: 0.5,
@@ -173,7 +173,7 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
                                 ),
                                 child: Text(
                                   authState.errorMessage!,
-                                  style: GoogleFonts.inter(color: AppColors.error, fontSize: 13),
+                                  style: GoogleFonts.karla(color: AppColors.error, fontSize: 13),
                                   textAlign: TextAlign.center,
                                 ),
                               ),
@@ -199,7 +199,7 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
                                 onPressed: authState.isLoading ? null : _handleLogin,
                                 style: FilledButton.styleFrom(
                                   backgroundColor: Colors.transparent,
-                                  foregroundColor: Colors.white,
+                                  foregroundColor: AppColors.onSurface,
                                   shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
                                   elevation: 0,
                                 ).copyWith(
@@ -209,11 +209,11 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
                                     ? const SizedBox(
                                         width: 24,
                                         height: 24,
-                                        child: CircularProgressIndicator(strokeWidth: 2, color: Colors.white),
+                                        child: CircularProgressIndicator(strokeWidth: 2, color: AppColors.onSurface),
                                       )
                                     : Text(
                                         'Sign In',
-                                        style: GoogleFonts.inter(fontWeight: FontWeight.w600, fontSize: 16, color: Colors.white),
+                                        style: GoogleFonts.karla(fontWeight: FontWeight.w600, fontSize: 16, color: AppColors.onSurface),
                                       ),
                               ),
                             ),
@@ -243,10 +243,10 @@ class _MobileLoginScreenState extends ConsumerState<MobileLoginScreen> {
     return TextFormField(
       controller: controller,
       obscureText: obscureText,
-      style: GoogleFonts.inter(color: AppColors.onSurface),
+      style: GoogleFonts.karla(color: AppColors.onSurface),
       decoration: InputDecoration(
         labelText: label,
-        labelStyle: GoogleFonts.inter(color: AppColors.onSurfaceVariant),
+        labelStyle: GoogleFonts.karla(color: AppColors.onSurfaceVariant),
         prefixIcon: Icon(icon, color: AppColors.onSurfaceVariant),
         suffixIcon: isPassword
           ? IconButton(