[FEATURE] Send prompt with selection to Claude Code

## Feature Description

Before sending a visual selection to Claude Code, allow prompts to be attached. The final piece sent to Claude should look like: `@filename#L1-10 selection prompt`, this should also be sent automatically.

## Use Case

At the moment the flow for prompting about a piece of code is this:
1. Make a selection
2. Send selection to claude code
3. Shift focus to Claude Code
4. Write additional prompt about the selection
5. Send.

The feature request would condense from 2-5 into one step.

## Proposed Solution

Something similar is implemented in [Opencode Nvim](https://github.com/nickjvandyke/opencode.nvim#ask--requireopencodeask) using the `ask()` function