feat: podcast demo mode with ALWRITY_ENABLED_FEATURES support

- Add ALWRITY_ENABLED_FEATURES env var for feature gating
- Podcast-only mode: skip LLM bootstrap, scheduler, persona services
- Enhance video generation prompt with scene context, analysis, narration
- Add voice cloning support via custom_voice_id in WaveSpeed
- Add text-to-speech for research results (browser speechSynthesis)
- Fix render queue to sync images from script phase
- Add WaveSpeed LLM pricing (gpt-oss-120b)
- Fix podcast bible generation error handling
- Refactor RouterManager for feature-based router loading

frontend/src/components/PodcastMaker/PodcastDashboard/utils.ts

@@ -4,6 +4,8 @@ import { CreateProjectPayload, Knobs } from "../types";
 export const DEFAULT_KNOBS: Knobs = {
   voice_emotion: "neutral",
   voice_speed: 1,
+  voice_id: "Wise_Woman",
+  custom_voice_id: undefined,
   resolution: "720p",
   scene_length_target: 45,
   sample_rate: 24000,