Ctrl+G should expand paste tokens to full text in $EDITOR (Claude Code parity)

### Describe the feature or problem you'd like to solve

When `compactPaste` is enabled (the default), pasting a large block collapses it in the compose box to a token like `[Paste #N - X lines]`. Pressing **Ctrl+G** ("edit prompt in `$EDITOR`") writes that **literal token** to the temp file, so I can't see or edit the actual pasted content in my external editor — I only see the placeholder. This is especially painful when using dictation software: I paste a long prompt and want to review/edit it in my editor before sending.

For comparison, Claude Code keeps the compact representation in the prompt box but expands it to the **full text** when you open the external editor.

### Proposed solution

When opening the prompt in `$EDITOR` via Ctrl+G, expand any paste tokens (`[Paste #N - X lines]` and `[Saved pasted content to workspace (...) id=N]`) to their full underlying text before writing the temp file. On save, ideally re-collapse the content back into tokens (or simply keep whatever text the user left).

This gives the best of both: a clean, compact compose box **and** a fully editable prompt in the external editor.

Today it's all-or-nothing via the `compactPaste` setting:

- `compactPaste: true` → compact box, but Ctrl+G shows only the token.
- `compactPaste: false` → Ctrl+G shows full text, but the box is no longer compact.

There's no way to get compact-in-box **and** full-text-in-editor at the same time.

### Example prompts or workflows

1. Dictate a 40-line prompt with speech-to-text, paste it (shows as `[Paste #1 - 40 lines]`), press Ctrl+G, and edit the full text in my editor before sending.
2. Paste a long log / stack trace, collapse it for a tidy box, then Ctrl+G to trim it down in `$EDITOR`.
3. Paste several large snippets (multiple tokens), open Ctrl+G once, and review / reorder them all as full text.
4. Compose a long multi-paragraph instruction across several pastes, then do a final full-text review in Vim / VS Code via Ctrl+G.

### Additional context

Observed in **v1.0.65** on **Windows (arm64)** with `EDITOR=notepad`.

From the bundled `app.js`, the Ctrl+G handler passes the raw compose-box buffer (with tokens) directly to the editor:

```js
// Ctrl+G handler
let cr = () => ot(Gn.text).then(({ content }) => Gn.setText(content));
```

The token-expansion function exists but is only invoked at **submit** time (replacing `[Paste #N]` with the in-memory text and `[Saved pasted content ...]` with a `` reference). It is not called — and isn't in scope — at the Ctrl+G handler. Routing Ctrl+G's input through that same expander would deliver this feature.

阅读捆绑后的 app.js 中的 Ctrl+G 处理器和现有的 token 展开路径。复现一次紧凑粘贴，打开 $EDITOR，并验证 paste tokens 在编辑器中会变成其完整文本，且编辑后的内容会返回 compose 流程。当多个 paste tokens（包括已保存的粘贴内容）都能通过此工作流处理时，即表示完成。

由索引模型根据 Issue 内容生成。