Feature Request: Visual Progress Indicator for File Deletion Operations

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

When Copilot performs long-running file deletion operations (e.g., deleting a directory with ~58,000 files), the UI provides almost no progress feedback. Users only see generic messages like "Still deleting ~58K files. Let me wait for it to finish." and "Waiting up to 180 seconds for command output." There is no indication of how many files have been deleted or how close the operation is to completing.

### Issue

### Proposed solution

Display a real-time progress indicator during file deletion operations. This could include:

- A running count of files deleted vs. total (e.g., "Deleted 12,400 / 57,907 files")
- A progress bar or percentage
- Estimated time remaining based on current deletion rate
- Optionally, a collapsible log showing individual file names as they are deleted

This would give users confidence that the operation is progressing and help them estimate when it will finish, rather than staring at repeated "Waiting up to N seconds" messages with no visibility into actual progress.

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### Example prompts or workflows

1. **"Delete the _boost_temp directory"** — Copilot deletes ~58K files. Instead of opaque wait messages, the user sees: `Deleting files... 34,200 / 57,907 (59%) — ~45s remaining`
2. **"Clean up all build artifacts in this repo"** — Copilot removes thousands of files across multiple directories. A progress bar updates in real time as each directory is cleared.
3. **"Remove node_modules and reinstall"** — Copilot deletes a large `node_modules` folder. The user sees file-by-file or batch progress instead of a spinning indicator with no context.

### Additional context

_No response_

該 issue 沒有指定檔案、測試或進入點，因此首先定位檔案刪除操作，以及輸出重複等待訊息的終端輸出。根據範例定義完成後的行為：長時間執行的刪除操作應顯示相對於總數的目前進度，並可選擇顯示時間估計或檔案記錄。

由索引模型根據 Issue 內容生成。