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/ui/PrimaryButton.tsx

@@ -7,9 +7,11 @@ interface PrimaryButtonProps {
   disabled?: boolean;
   loading?: boolean;
   startIcon?: React.ReactNode;
+  endIcon?: React.ReactNode;
   tooltip?: string;
   ariaLabel?: string;
   sx?: SxProps<Theme>;
+  size?: "small" | "medium" | "large";
 }
 
 export const PrimaryButton: React.FC<PrimaryButtonProps> = ({
@@ -18,24 +20,32 @@ export const PrimaryButton: React.FC<PrimaryButtonProps> = ({
   disabled = false,
   loading = false,
   startIcon,
+  endIcon,
   tooltip,
   ariaLabel,
   sx,
+  size = "medium",
 }) => {
+  const sizeStyles = {
+    small: { px: 1.5, py: 0.5, fontSize: "0.75rem" },
+    medium: { px: 3, py: 1, fontSize: "0.875rem" },
+    large: { px: 4, py: 1.5, fontSize: "1rem" },
+  };
+
   const button = (
     <Button
       variant="contained"
       onClick={onClick}
       disabled={disabled || loading}
       startIcon={loading ? <CircularProgress size={16} /> : startIcon}
+      endIcon={loading ? undefined : endIcon}
       aria-label={ariaLabel}
       sx={{
         background: "linear-gradient(135deg, #667eea 0%, #764ba2 100%)",
         color: "white",
         fontWeight: 600,
         textTransform: "none",
-        px: 3,
-        py: 1,
+        ...sizeStyles[size],
         "&:hover": {
           background: "linear-gradient(135deg, #764ba2 0%, #667eea 100%)",
         },