Add option to disable auto-opening diff view on file edit

Question

## Problem

When Claude Code edits a file via the VS Code extension, the diff view automatically opens in the editor area, pushing down the terminal panel. This is very disruptive, especially when working with multiple terminals.

## Expected behavior

A setting to disable auto-opening the diff view, e.g.:
```json
"claude-code.revealDiffOnEdit": false
```

File edits would still apply, but without forcing the editor to reveal the diff and steal focus from the terminal.

## Environment

- VS Code