[FEATURE] Show progress indicator during context compaction

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The Claude desktop application displays a progress bar and percentage when compacting the conversation context. The CLI gives no feedback during this operation, which can make it appear frozen.

Proposed Solution

Add a progress indicator (e.g., a spinner with percentage) to the terminal output during compaction, similar to what the desktop application already shows.

When compaction starts, show something like:
⠋ Compacting conversation... 42%
and clear it (or replace with a completion message) when done.

Alternative Solutions

_No response_

Priority

Low - Nice to have

Feature Category

Interactive mode (TUI)

Use Case Example

Running /compact on a large session (or when it occurs automatically) can take 10–20 seconds with no feedback. A progress indicator reassures the user that the tool is working and gives a sense of how long to wait.

Additional Context

How it appears today:

<img width="288" height="104" alt="Image" src="https://github.com/user-attachments/assets/16f253b9-1a3c-4509-b7bb-66cf570f7e47" />