bug: Conversation history doesn't persist when /context add is used

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

macOS

### Expected behaviour

When running `q chat --resume` in the same directory, the previous conversation should be restored

### Actual behaviour

Conversation history fails to persist when the `/context add` command is used:

1. After using `/context add`, subsequent conversation responses are not saved
2. When running `q chat --resume`, the previous conversation history is lost in favor of the one before that

### Steps to reproduce

## Step 1: Start a basic conversation

```console
$ q chat
> Introduce yourself
[Q introduces itself]
> /quit
```

## Step 2: Verify conversation persists

```console
$ q chat --resume
Picking up where we left off...
[Q shows a summary of its introduction]
> /quit
```

## Step 3: Add context and have conversation

```console
$ q chat
> /context add README.md
> Summarize the context
[Q provides summary of README.md]
> /quit

## Step 4: Restart - conversation history is lost

```console
$ q chat --resume
Picking up where we left off...
> [Q shows a summary of its introduction, not the summary of its context]
```

### Environment

```yaml

```