feat: Murattal player enhancements & prayer schedule auto-scroll

- Murattal: Spotify-style 5-button controls [Shuffle, Prev, Play, Next, Playlist]
- Murattal: Animated 7-bar equalizer visualization in player circle
- Murattal: Unsplash API background with frosted glass player overlay
- Murattal: Transparent AppBar with backdrop blur
- Murattal: Surah playlist bottom sheet with full 114 Surah list
- Murattal: Auto-play disabled on screen open, enabled on navigation
- Murattal: Shuffle mode for random Surah playback
- Murattal: Photographer attribution per Unsplash guidelines
- Dashboard: Auto-scroll prayer schedule to next active prayer
- Fix: setState lifecycle errors on Reading & Murattal screens
- Setup: flutter_dotenv, cached_network_image, url_launcher deps

lib/core/providers/theme_provider.dart

@@ -0,0 +1,12 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:hive_flutter/hive_flutter.dart';
+import '../../data/local/hive_boxes.dart';
+import '../../data/local/models/app_settings.dart';
+
+/// Theme mode state provider.
+final themeProvider = StateProvider<ThemeMode>((ref) {
+  final box = Hive.box<AppSettings>(HiveBoxes.settings);
+  final settings = box.get('default');
+  return settings?.themeModeIndex == 1 ? ThemeMode.light : ThemeMode.dark;
+});