Define Festival TypeScript types

[AngusHsu]

Description

Create the core Festival type definition at src/types/festival.ts.

Fields

• id — unique string identifier (e.g. chinese-new-year)
• name — { zh: string; en: string } (Chinese + English)
• lunarDate — { month: number; day: number } (lunar calendar)
• description — { zh: string; en: string } (what the festival is about)
• offerings — array of offering items (供品), each with name and optional description
• rituals — array of ritual steps (拜拜流程)
• images — array of image references (path or URL)
• tags — string array for categorization (e.g. ancestor, deity, ghost)

Acceptance Criteria

• src/types/festival.ts exists with exported types
• Types are strict and well-documented
• Build passes