Add complete travel postcard AIGC creation workflow including:
- New AIGC pages: template selection home, result detail, and history records
- Reusable UI components: template card, flow steps, result preview, action buttons, record lists
- Static assets including template images, fonts and styles
- Updated TopNavBar component to support menu button alignment
- Register new AIGC page routes in pages.json
- Add mock data for templates, user records and result details
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