Copy rewrapped should handle with nested quotes

I just encountered this case where I want to copy-paste hunks of the following out of a Claude Code session:

```
Biggest copy regression: Tiling Layout

This section lost its selling power. Previous version
sold the use case:

▎ "Run builds, agents, servers, and scripts side by
▎ side. Minimize the ones you're not watching to a
▎ compact status indicator — every pane keeps running
▎ and every alert still fires whether minimized or
▎ not."

Current version (lines 35–39) sells the mechanics:

▎ "You can spawn, layout, and relayout everything in
▎ the terminal using any of: default tmux shortcuts,
▎ intuitive modern shortcuts, the mouse"

Readers on a marketplace decide based on "can I
picture myself using this?" The old version paints
that picture; the new version reads like a feature
inventory. Also: the heading promises "Minimize /
Maximize" but the body never mentions either — the
feature claim is in the keyboard table only.
```

Here is what "Copy rewrapped" does right now:

```
Biggest copy regression: Tiling Layout

This section lost its selling power. Previous version sold the use case:

▎ "Run builds, agents, servers, and scripts side by ▎ side. Minimize the ones you're not watching to a ▎ compact status indicator — every pane keeps running ▎ and every alert still fires whether minimized or ▎ not."

Current version (lines 35–39) sells the mechanics:

▎ "You can spawn, layout, and relayout everything in ▎ the terminal using any of: default tmux shortcuts, ▎ intuitive modern shortcuts, the mouse"

Readers on a marketplace decide based on "can I picture myself using this?" The old version paints that picture; the new version reads like a feature inventory. Also: the heading promises "Minimize / Maximize" but the body never mentions either — the feature claim is in the keyboard table only.

Suggested direction: lead with the use case, then note that you can drive it with mouse/modern shortcuts/tmux shortcuts.
```

Should probably use the markdown `>` convention to deal with nesting like this.

从 Copy rewrapped 命令或操作开始，复现 issue 中嵌套引用的示例，并检查 Markdown blockquote 标记的处理方式。完成的标准是：复制的文本保留嵌套的 `>` 结构，而不是将引用行扁平化，同时现有的复制行为保持不变。

由索引模型根据 Issue 内容生成。