Fix strict type failures after Vite upgrade

[freizl]

Summary

• guard all data lookups and route params so stricter type checking introduced by the Vite upgrade passes
• add fallbacks and validations for XiCi/Gua/Gua tables so undefined values never reach the UI
• rerun build (type-check + lint + vite build) to ensure the pipeline is green again

[netlify]

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