feat(phase-4): UI/UX improvements for Podcast Maker Write phase

Frontend Changes:
- Add scene numbering badge (1/N) next to scene titles
- Add inline status chips (Complete, Audio, Image, Voice, Why Script)
- Professional AI-like gradient styling for all chips with shadows
- Remove Script Editor header and 'Why This Script Format?' collapsible
- Move Voice and Why Script info to per-scene chips
- Make scene section mobile-responsive (responsive layout, button sizing)
- Rename 'B-Roll Charts' to 'Podcast Charts' with accordion (collapsed by default)
- Add sceneIndex prop to SceneEditor for scene numbering
- Enhanced accessibility with keyboard navigation and focus states

Backend Changes:
- Audio handler improvements
- B-roll handler enhancements
- Script handler updates
- B-roll composer and service improvements
- Removed temporary broll_temp files

Technical:
- Full mobile responsiveness for scene cards
- Gradient chip styling: vibrant colors with white text and shadows
- Non-breaking approval/generation flow preserved
- TypeScript compatibility maintained

frontend/src/services/podcastApi.ts

@@ -626,11 +626,14 @@ export const podcastApi = {
       text: textToUse,
       voice_id: params.voiceId || "Wise_Woman",
       custom_voice_id: params.customVoiceId || null,
-      speed: params.speed ?? 1.0, // Normal speed (was 0.9, but too slow - causing duration issues)
+      use_voice_clone: params.useVoiceClone || false,
+      voice_sample_url: params.voiceSampleUrl || null,
+      voice_clone_engine: params.voiceCloneEngine || null,
+      speed: params.speed ?? 1.0,
       volume: params.volume ?? 1.0,
       pitch: params.pitch ?? 0.0,
       emotion: sceneEmotion,
-      english_normalization: params.englishNormalization ?? true, // Better number reading for statistics
+      english_normalization: params.englishNormalization ?? true,
       sample_rate: params.sampleRate || null,
       bitrate: params.bitrate || null,
       channel: params.channel || null,