+data caching

[brillout]

Description

Use cases:

• Avoid re-fetching the +data of layouts, see https://github.com/vikejs/vike/issues/1833#issuecomment-2324900026.
• Avoid re-fetching global +data (e.g. pages/+data).
  • Upon client-side navigation.
  • Forever cache. (Similar to +onBoot but different: +data is called lazily upon rendering a page, whereas +onBoot is called eagerly upon starting the server/pre-rendering.)
• More use cases?

[itsezc]

This would also be very useful for passing data to +Layout if at all possible, think Auth / Profile details for tools such as Firebase

[brillout]

Closing in favor of:

• https://github.com/vikejs/vike/issues/2566