Preserve composer hyperlinks across wrapped lines (#40720)

## What changed

- Detect visible HTTP(S) URLs in the composer and attach the complete OSC 8 destination to every wrapped fragment, including when part of the URL is scrolled offscreen.
- Cache hyperlink metadata with the textarea wrap state while leaving masked input and destinations larger than 8 KiB unannotated.
- Make shared hyperlink mapping grapheme-aware, recognize Unicode whitespace boundaries, and scan URLs and trailing delimiters incrementally for large inputs.

## Testing

- Add coverage for wrapped and scrolled URLs, joined emoji, Unicode whitespace, preserved highlighting, masked input, cache invalidation, oversized destinations, and drafts containing many URLs.

GitOrigin-RevId: 40facdf2fe79438c91c82bff2d849c342f1ab28a