fix(flutter): 优化播放加载占位与主题色

lib/pages/player/player_view.dart

@@ -20,6 +20,7 @@ import '../../core/theme/app_colors.dart';
 import '../../core/theme/app_theme.dart';
 import '../../core/widgets/auth_gate.dart';
 import '../../core/widgets/download_action.dart';
+import '../../core/widgets/remote_image.dart';
 import '../../l10n/app_localizations.dart';
 import 'player_binding.dart';
 import 'player_logic.dart';
@@ -298,11 +299,7 @@ class _PlayerPageState extends State<PlayerPage> with WidgetsBindingObserver {
     return Stack(
       fit: StackFit.expand,
       children: [
-        if (!ready)
-          const ColoredBox(
-            key: Key('player-fallback-background'),
-            color: Colors.black,
-          ),
+        if (!ready) _PlayerFallbackBackground(posterUrl: drama.posterUrl),
         ?video,
         if (widget.homeMode && _chromeVisible && !logic.chromeHidden)
           Positioned.fill(
@@ -316,7 +313,10 @@ class _PlayerPageState extends State<PlayerPage> with WidgetsBindingObserver {
         // 票据三态之一：起播前正在向后端要签名地址
         if (selected && logic.ticketLoading)
           const Center(
-            child: CircularProgressIndicator(color: AppColors.blueSoft),
+            child: CircularProgressIndicator(
+              key: Key('player-ticket-loading'),
+              color: AppColors.blue,
+            ),
           ),
         // 票据三态之二：拿票失败（断网/服务异常）→ 可重试，不假装在加载
         if (selected && !logic.ticketLoading && logic.ticketError != null)
@@ -348,7 +348,10 @@ class _PlayerPageState extends State<PlayerPage> with WidgetsBindingObserver {
           ),
         if (selected && logic.session.loading)
           const Center(
-            child: CircularProgressIndicator(color: AppColors.blueSoft),
+            child: CircularProgressIndicator(
+              key: Key('player-session-loading'),
+              color: AppColors.blue,
+            ),
           ),
         if (selected && !ready && logic.session.error != null)
           Center(
@@ -550,3 +553,34 @@ class _PlayerPageState extends State<PlayerPage> with WidgetsBindingObserver {
     );
   }
 }
+
+class _PlayerFallbackBackground extends StatelessWidget {
+  const _PlayerFallbackBackground({required this.posterUrl});
+
+  final String posterUrl;
+
+  @override
+  Widget build(BuildContext context) {
+    if (posterUrl.trim().isEmpty) {
+      return const ColoredBox(
+        key: Key('player-fallback-background'),
+        color: Colors.black,
+      );
+    }
+    return Stack(
+      key: const Key('player-fallback-background'),
+      fit: StackFit.expand,
+      children: [
+        RemoteImage(
+          posterUrl,
+          key: const Key('player-fallback-cover'),
+          fit: BoxFit.cover,
+        ),
+        const ColoredBox(
+          key: Key('player-fallback-scrim'),
+          color: Color(0x66000000),
+        ),
+      ],
+    );
+  }
+}