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/themed_loading_screen.dart

@@ -2,43 +2,48 @@ import 'package:flutter/material.dart';
 import 'package:google_fonts/google_fonts.dart';
 import '../theme/app_colors.dart';
 
-/// Stitch-themed loading screen with dark gradient and blue accent.
+/// Écran de chargement « Warm Cinema » — salle qui s'éteint avant projection.
 class ThemedLoading extends StatelessWidget {
   const ThemedLoading({super.key});
 
   @override
   Widget build(BuildContext context) {
-    return Container(
-      decoration: const BoxDecoration(
-        gradient: LinearGradient(
-          begin: Alignment.topLeft,
-          end: Alignment.bottomRight,
-          colors: [
-            Color(0xFF0F1014), // Deep Space Dark
-            Color(0xFF121317), // Stitch background
-          ],
-        ),
-      ),
+    return const DecoratedBox(
+      decoration: BoxDecoration(gradient: AppColors.backgroundGradient),
       child: Center(
         child: Column(
           mainAxisSize: MainAxisSize.min,
           children: [
-            const CircularProgressIndicator(
-              color: Color(0xFF4b8eff), // AppColors.primaryContainer
-              strokeWidth: 3,
-            ),
-            const SizedBox(height: 16),
-            Text(
-              'Loading...',
-              style: GoogleFonts.inter(
-                color: AppColors.onSurfaceVariant,
-                fontSize: 14,
-                fontWeight: FontWeight.w500,
+            SizedBox(
+              width: 34,
+              height: 34,
+              child: CircularProgressIndicator(
+                color: AppColors.primaryContainer,
+                strokeWidth: 2,
               ),
             ),
+            SizedBox(height: 20),
+            _LoadingLabel(),
           ],
         ),
       ),
     );
   }
 }
+
+class _LoadingLabel extends StatelessWidget {
+  const _LoadingLabel();
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(
+      'PROJECTION',
+      style: GoogleFonts.karla(
+        color: AppColors.textTertiary,
+        fontSize: 11,
+        fontWeight: FontWeight.w700,
+        letterSpacing: 3.2,
+      ),
+    );
+  }
+}