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/app/theme/app_theme.dart

@@ -0,0 +1,90 @@
+import 'package:flutter/material.dart';
+import 'app_colors.dart';
+import 'app_text_styles.dart';
+
+/// ThemeData for light and dark modes, Material 3 enabled.
+class AppTheme {
+  AppTheme._();
+
+  static ThemeData get light => ThemeData(
+        useMaterial3: true,
+        brightness: Brightness.light,
+        colorScheme: AppColors.lightColorScheme,
+        scaffoldBackgroundColor: AppColors.backgroundLight,
+        textTheme: AppTextStyles.textTheme.apply(
+          bodyColor: AppColors.textPrimaryLight,
+          displayColor: AppColors.textPrimaryLight,
+        ),
+        appBarTheme: const AppBarTheme(
+          backgroundColor: Colors.transparent,
+          elevation: 0,
+          scrolledUnderElevation: 0,
+          centerTitle: true,
+          iconTheme: IconThemeData(color: AppColors.textPrimaryLight),
+          titleTextStyle: TextStyle(
+            color: AppColors.textPrimaryLight,
+            fontSize: 20,
+            fontWeight: FontWeight.w700,
+          ),
+        ),
+        bottomNavigationBarTheme: const BottomNavigationBarThemeData(
+          backgroundColor: AppColors.surfaceLight,
+          selectedItemColor: AppColors.primary,
+          unselectedItemColor: AppColors.textSecondaryLight,
+          type: BottomNavigationBarType.fixed,
+          elevation: 0,
+        ),
+        cardTheme: CardThemeData(
+          color: AppColors.surfaceLight,
+          elevation: 0,
+          shape: RoundedRectangleBorder(
+            borderRadius: BorderRadius.circular(16),
+            side: BorderSide(
+              color: AppColors.cream,
+            ),
+          ),
+        ),
+        dividerColor: AppColors.cream,
+      );
+
+  static ThemeData get dark => ThemeData(
+        useMaterial3: true,
+        brightness: Brightness.dark,
+        colorScheme: AppColors.darkColorScheme,
+        scaffoldBackgroundColor: AppColors.backgroundDark,
+        textTheme: AppTextStyles.textTheme.apply(
+          bodyColor: AppColors.textPrimaryDark,
+          displayColor: AppColors.textPrimaryDark,
+        ),
+        appBarTheme: const AppBarTheme(
+          backgroundColor: Colors.transparent,
+          elevation: 0,
+          scrolledUnderElevation: 0,
+          centerTitle: true,
+          iconTheme: IconThemeData(color: AppColors.textPrimaryDark),
+          titleTextStyle: TextStyle(
+            color: AppColors.textPrimaryDark,
+            fontSize: 20,
+            fontWeight: FontWeight.w700,
+          ),
+        ),
+        bottomNavigationBarTheme: const BottomNavigationBarThemeData(
+          backgroundColor: AppColors.surfaceDark,
+          selectedItemColor: AppColors.primary,
+          unselectedItemColor: AppColors.textSecondaryDark,
+          type: BottomNavigationBarType.fixed,
+          elevation: 0,
+        ),
+        cardTheme: CardThemeData(
+          color: AppColors.surfaceDark,
+          elevation: 0,
+          shape: RoundedRectangleBorder(
+            borderRadius: BorderRadius.circular(16),
+            side: BorderSide(
+              color: AppColors.primary.withValues(alpha: 0.1),
+            ),
+          ),
+        ),
+        dividerColor: AppColors.surfaceDark,
+      );
+}