feat: Improve text segmentation for faster playback

Implement a progressive text segmentation strategy. The first few segments are intentionally kept very short to allow playback to start almost immediately, creating a more responsive feel. As more segments are processed, their length gradually increases to optimize audio generation efficiency for the remainder of the article. Additionally, the title is now prepended as the very first segment. The buffer ahead is also increased to 5 segments to ensure content is ready.

Further refinements include:
- Enhanced voice descriptions in constants.
- Improved segment styling in ReaderView for better visual active state indication.

constants.ts

@@ -1,15 +1,16 @@
+
 import { VoiceName } from './types';
 
 export const AVAILABLE_VOICES = [
-  { name: VoiceName.Puck, label: 'Puck (Male, Standard)' },
-  { name: VoiceName.Charon, label: 'Charon (Male, Deep)' },
-  { name: VoiceName.Kore, label: 'Kore (Female, Soothing)' },
-  { name: VoiceName.Fenrir, label: 'Fenrir (Male, Energetic)' },
-  { name: VoiceName.Zephyr, label: 'Zephyr (Female, Clear)' },
+  { name: VoiceName.Puck, label: 'Puck (Standard American, Male)' },
+  { name: VoiceName.Charon, label: 'Charon (Deep, Authoritative Male)' },
+  { name: VoiceName.Kore, label: 'Kore (Soft, Calm Female)' },
+  { name: VoiceName.Fenrir, label: 'Fenrir (Energetic, Mid-Atlantic Male)' },
+  { name: VoiceName.Zephyr, label: 'Zephyr (Clear, Professional Female)' },
 ];
 
 export const MIN_SPEED = 0.5;
 export const MAX_SPEED = 3.5;
 export const SPEED_STEP = 0.5;
 
-export const SAMPLE_RATE = 24000;
+export const SAMPLE_RATE = 24000;