Implement script generation endpoint (Task 18)

- Added ScriptRequest, ScriptResponse, and ScriptSegment Pydantic models
- Created /api/tts/script POST endpoint in main.py
- Integrated with TTSService to generate script segments using AI
- Added generate_script_segments method to TTSService
- Returns segments with unique IDs for frontend tracking
- Handles errors gracefully when AI segmentation fails
- Falls back to pattern-based segmentation when Ollama unavailable
- Added comprehensive tests for the endpoint
- Validates: Requirements 15.1, 15.2

.kiro/specs/text-to-audiobook/tasks.md

@@ -349,15 +349,125 @@
   - Add troubleshooting section for Ollama issues
   - _Requirements: 14.6_
 
-- [ ] 18. Final integration testing and polish
-  - Test complete end-to-end workflow
-  - Test with various text samples (short, long, multiple roles, no roles)
+- [x] 18. Implement script generation endpoint
+  - Create /api/tts/script POST endpoint in main.py
+  - Define ScriptRequest and ScriptResponse Pydantic models
+  - Define ScriptSegment model with id, speaker, and text fields
+  - Integrate with TTSService to generate script segments using AI
+  - Return segments with unique IDs for frontend tracking
+  - Handle errors gracefully when AI segmentation fails
+  - _Requirements: 15.1, 15.2_
+
+- [ ]* 18.1 Write property test for script generation
+  - **Property 32: Script generation completeness**
+  - **Validates: Requirements 15.2**
+
+- [ ]* 18.2 Write property test for script segment structure
+  - **Property 33: Script segment structure**
+  - **Validates: Requirements 15.4**
+
+- [ ]* 18.3 Write unit tests for script endpoint
+  - Test successful script generation
+  - Test with various text lengths
+  - Test error handling
+  - _Requirements: 15.2_
+
+- [ ] 19. Update TTS generation endpoint to accept edited scripts
+  - Modify TTSRequest to accept optional segments array
+  - Update generate_audiobook logic to use segments if provided
+  - Fall back to text segmentation if no segments provided
+  - Ensure backward compatibility with existing API calls
+  - _Requirements: 15.7_
+
+- [ ]* 19.1 Write property test for edited script persistence
+  - **Property 35: Edited script persistence**
+  - **Validates: Requirements 15.7**
+
+- [ ]* 19.2 Write unit tests for script-based generation
+  - Test generation with edited segments
+  - Test fallback to text-based generation
+  - Test segment speaker assignments are respected
+  - _Requirements: 15.7_
+
+- [ ] 20. Implement script generation API client function
+  - Add generateScript() function to src/api/tts.ts
+  - Define ScriptSegment, ScriptRequest, and ScriptResponse TypeScript interfaces
+  - Implement error handling for script generation
+  - Update GenerateRequest interface to support segments
+  - _Requirements: 15.1, 15.2_
+
+- [ ]* 20.1 Write unit tests for script API client
+  - Test generateScript() function
+  - Test error handling
+  - Mock API responses
+  - _Requirements: 15.1_
+
+- [ ] 21. Implement ScriptReviewSection component
+  - Create ScriptReviewSection component
+  - Display list of script segments with text boxes
+  - Add speaker dropdown for each segment
+  - Implement segment editing handlers
+  - Add "Generate Audiobook" button
+  - Add "Skip Review" button for quick generation
+  - Style for readability and mobile responsiveness
+  - _Requirements: 15.3, 15.4, 15.5, 15.6, 15.8_
+
+- [ ]* 21.1 Write property test for script segment editability
+  - **Property 34: Script segment editability**
+  - **Validates: Requirements 15.5**
+
+- [ ]* 21.2 Write unit tests for ScriptReviewSection
+  - Test component renders segments correctly
+  - Test speaker dropdown contains all roles
+  - Test segment editing updates state
+  - Test generate button is enabled
+  - Test skip review button works
+  - _Requirements: 15.3, 15.4, 15.5, 15.8_
+
+- [ ] 22. Update App component for script review workflow
+  - Add 'review' phase to application state
+  - Add scriptSegments state variable
+  - Add isGeneratingScript loading state
+  - Implement handleGenerateScript() method
+  - Implement handleSkipReview() method
+  - Implement handleSegmentChange() method
+  - Update handleGenerate() to use edited segments
+  - Wire up ScriptReviewSection component
+  - Update phase transitions: input → assignment → review → generated
+  - _Requirements: 15.1, 15.3, 15.6, 15.7, 15.8_
+
+- [ ]* 22.1 Write unit tests for script workflow
+  - Test phase transitions include review phase
+  - Test script generation is called after voice assignment
+  - Test segment changes are tracked
+  - Test skip review bypasses review phase
+  - _Requirements: 15.1, 15.8_
+
+- [ ] 23. Update VoiceAssignmentSection to trigger script generation
+  - Change "Generate Audiobook" button to "Next: Review Script"
+  - Add "Skip Review & Generate" button as alternative
+  - Update button handlers to call appropriate methods
+  - _Requirements: 15.1, 15.8_
+
+- [ ] 24. Add script review documentation
+  - Document script review feature in README
+  - Add screenshots of script review interface
+  - Explain how to edit speaker assignments
+  - Document skip review option
+  - Add troubleshooting for script generation issues
+  - _Requirements: 15.3, 15.4, 15.5, 15.8_
+
+- [ ] 25. Final integration testing and polish
+  - Test complete end-to-end workflow with script review
+  - Test script generation with various text samples
+  - Test editing speaker assignments in script
+  - Test skip review functionality
   - Test with unmarked dialogue text (relying on AI detection)
   - Test with marked text (pattern detection)
   - Test with Ollama available and unavailable
   - Test all language options (a, b, f, j)
   - Test error scenarios (network failures, invalid inputs)
-  - Verify audio quality and playback
+  - Verify audio quality and playback with edited scripts
   - Test Docker deployment
   - Fix any bugs discovered during testing
   - _Requirements: All_