[Feature request] Add optional annotation metadata (authors, timestamps) to Details

### Description

When more than one person is annotating a design file, it's not always clear who annotated what. Figma doesn't offer metadata for when layers or component instances were added or modified on the canvas, which makes it hard to track annotation history.

### Requested change

Add optional metadata fields to annotations, such as:

- **Author:** The name or handle of the person who created the annotation
- **Date/time:** When the annotation was added or last updated

### Open questions

- Should this be added directly to Details annotations (alongside existing fields like documentation links), or as a separate lightweight utility component?
- Would adding more properties to already property-heavy Details annotations be too much? A standalone summary utility might be a cleaner approach.
- This could also be set up as a sub-component on the "Customize this kit" page, so teams can opt into it without it being enabled by default.

Start by reviewing the existing Details annotations and the “Customize this kit” page to determine where optional metadata belongs. Compare inline fields with a standalone utility, then define the chosen approach and verify that author and date/time metadata can be enabled without changing the default kit.

索引モデルが issue の本文から書いたものです。