feat: Update VoiceAssignmentSection to trigger script generation

- Changed 'Generate Audiobook' button to 'Next: Review Script'
- Added 'Skip Review & Generate' button as alternative
- Updated button handlers to call handleGenerateScript and handleSkipReview
- Updated button styling: primary button now blue for review, green for skip
- Maintains backward compatibility with optional onSkipReview prop

Requirements: 15.1, 15.8

frontend/src/components/VoiceAssignmentSection.tsx

@@ -9,6 +9,7 @@ interface VoiceAssignmentSectionProps {
   speed: number;
   onSpeedChange: (speed: number) => void;
   onGenerate: () => void;
+  onSkipReview?: () => void;
   isGenerating: boolean;
   allRolesAssigned: boolean;
 }
@@ -138,6 +139,7 @@ export default function VoiceAssignmentSection({
   speed,
   onSpeedChange,
   onGenerate,
+  onSkipReview,
   isGenerating,
   allRolesAssigned,
 }: VoiceAssignmentSectionProps) {
@@ -223,19 +225,33 @@ export default function VoiceAssignmentSection({
         </div>
       </div>
 
-      {/* Generate Button */}
-      <div className="flex justify-center">
+      {/* Action Buttons */}
+      <div className="flex flex-col sm:flex-row justify-center gap-3 sm:gap-4">
         <button
           onClick={onGenerate}
           disabled={isGenerateDisabled}
           className={`w-full sm:w-auto px-8 py-3 min-h-[44px] rounded-lg font-semibold text-white transition-colors touch-manipulation ${
             isGenerateDisabled
               ? 'bg-gray-400 cursor-not-allowed'
-              : 'bg-green-600 hover:bg-green-700 active:bg-green-800 cursor-pointer'
+              : 'bg-blue-600 hover:bg-blue-700 active:bg-blue-800 cursor-pointer'
           }`}
         >
-          {isGenerating ? 'Generating...' : 'Generate Audiobook'}
+          {isGenerating ? 'Generating Script...' : 'Next: Review Script'}
         </button>
+        
+        {onSkipReview && (
+          <button
+            onClick={onSkipReview}
+            disabled={isGenerateDisabled}
+            className={`w-full sm:w-auto px-8 py-3 min-h-[44px] rounded-lg font-semibold text-white transition-colors touch-manipulation ${
+              isGenerateDisabled
+                ? 'bg-gray-400 cursor-not-allowed'
+                : 'bg-green-600 hover:bg-green-700 active:bg-green-800 cursor-pointer'
+            }`}
+          >
+            Skip Review & Generate
+          </button>
+        )}
       </div>
 
       {/* Validation Message */}