Make Ctrl+E accept inline autocomplete suggestions

Describe the feature or problem you'd like to solve

When an inline suggestion is visible,  Ctrl+E  should accept it, matching common Emacs-style terminal behavior. Otherwise, it should continue moving the cursor to the end of the line.

Proposed solution

Make  Ctrl+E  context-sensitive:

• If an inline suggestion is visible, accept the entire suggestion.
• If no inline suggestion is visible, keep the existing behavior of moving the cursor to the end of the line.

Example prompts or workflows

I type:

Explain the changes in src/

Copilot displays a ghost suggestion:

Explain the changes in src/auth.ts since the last commit

Pressing  Ctrl+E  should accept the full ghost text. If there is no ghost suggestion,  Ctrl+E  should simply move the cursor to the end of the current line.

Additional context

No response

该 issue 没有指明任何 repository 文件或测试。首先定位 CLI 的 Ctrl+E 按键处理逻辑和接受内联建议的入口点，然后追踪现有的行尾行为。完成的标准是：Ctrl+E 接受完整的可见建议，并且在没有建议时仍移动到行尾；如果有相关的终端交互测试，请添加或运行它们。