Preserve logical source text and styles across TUI wrapping - #46708

## Why

Display wrapping removes whitespace and adds gutters, so rendered rows alone cannot reliably describe the original logical text. Streaming previews also need to detect source changes that leave visible rows unchanged.

## What changed

- Retain shared logical text, styles, exact byte ranges, and display margins alongside wrapped rows; remap hyperlinks using those ranges.
- Preserve source metadata through prompt, Markdown, and prefixed history rendering, including spoken artifact annotations. Clear it when split-flap animation replaces the text.
- Include source metadata when comparing streaming previews and agent or plan tails.
- Keep compound graphemes intact, preserve explicit span styles, and reuse first-fit wrapping results when safe.
- Use the lighter history prompt background for submitted messages.

## Testing

Add regression coverage for source ranges and styles across widths and gutters, distinct repeated lines, source-only streaming updates, compound graphemes, and equivalence between reused and generic wrapping results. Extend Markdown, spoken artifact, and animation tests to check retained source metadata.

GitOrigin-RevId: 9e60746642fc9a8f91c1abfe7c77eefc1fe421ab