feat: Introduce reader settings and dark mode support

Adds a new `ReaderSettings` type to manage user preferences such as dark mode, font size, line height, font family, and auto-scroll behavior.

Implements dark mode styling for various UI components including the `VoiceSelector` and `QueueItem`, enhancing visual consistency.

Enhances the `ReaderView` component to respect the `autoScroll` setting and introduces basic text styling options based on the new settings.

components/VoiceSelector.tsx

@@ -1,3 +1,4 @@
+
 import React from 'react';
 import { VoiceName } from '../types';
 import { AVAILABLE_VOICES } from '../constants';
@@ -12,12 +13,12 @@ interface VoiceSelectorProps {
 export const VoiceSelector: React.FC<VoiceSelectorProps> = ({ selectedVoice, onVoiceChange, disabled }) => {
   return (
     <div className="flex items-center space-x-2">
-      <Mic className="w-4 h-4 text-slate-500" />
+      <Mic className="w-4 h-4 text-slate-500 dark:text-slate-400" />
       <select
         value={selectedVoice}
         onChange={(e) => onVoiceChange(e.target.value as VoiceName)}
         disabled={disabled}
-        className="bg-white border border-slate-300 text-slate-700 text-sm rounded-lg focus:ring-blue-500 focus:border-blue-500 block w-full p-2.5 disabled:opacity-50 disabled:cursor-not-allowed"
+        className="bg-white dark:bg-slate-800 border border-slate-300 dark:border-slate-700 text-slate-700 dark:text-slate-200 text-sm rounded-lg focus:ring-blue-500 focus:border-blue-500 block w-full p-2.5 disabled:opacity-50 disabled:cursor-not-allowed transition-colors duration-300"
       >
         {AVAILABLE_VOICES.map((v) => (
           <option key={v.name} value={v.name}>
@@ -27,4 +28,4 @@ export const VoiceSelector: React.FC<VoiceSelectorProps> = ({ selectedVoice, onV
       </select>
     </div>
   );
-};
+};