kiro-cli not updating since version 2.19.0

### 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

Linux 7.0.0-1011-aws - Ubuntu 26.04 LTS

### Expected behaviour

kiro-cli must update as soon there is one available.

### Actual behaviour

kiro-cli ceased to update. Below is the error that occurs in the end of update process:

$ kiro-cli update
████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████ 100/100error: failed to unpack `/tmp/.tmpCrmUAf/kirocli/bin/kiro-cli-chat`

If this is unexpected, try running kiro-cli doctor and then try again.

### Steps to reproduce

$ kiro-cli update
████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████ 100/100error: failed to unpack `/tmp/.tmpCrmUAf/kirocli/bin/kiro-cli-chat`

If this is unexpected, try running kiro-cli doctor and then try again.

$ kiro-cli doctor

✔ Everything looks good!

Kiro CLI still not working? Run kiro-cli issue to let us know!

### Environment

```yaml

[q-details]
version = "2.19.0"
hash = "60eb656b3201c6e0a5b800c3b9dde677e0e33396"
date = "2026-08-19T22:22:48.411638Z (9d ago)"
variant = "minimal"

[system-info]
chip = "Intel(R) Xeon(R) CPU E5-2686 v4 @ 2.30GHz"
total-cores = 2
memory = "3.82 GB"

[system-info.os.linux]
kernel_version = "7.0.0-1011-aws"
id = "ubuntu"
name = "Ubuntu"
pretty_name = "Ubuntu 26.04 LTS"
version_id = "26.04"
version = "26.04 LTS (Resolute Raccoon)"

[environment]
cwd = "/home/USER/Documents/prj002_altcoin_screener"
cli-path = "/home/USER/Documents/prj002_altcoin_screener"
os = "Linux"
shell-path = "/usr/bin/bash"
shell-version = "5.3.9"
install-method = "unknown"
in-ssh = true

[env-vars]
PATH = "/home/USER/.npm-global/bin:/home/USER/.local/bin:/home/USER/.npm-global/bin:/home/USER/anaconda3/bin:/home/USER/anaconda3/condabin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/USER/.local/bin"
QTERM_SESSION_ID = "ce601a6bbc6644df8eb5478e639e8362"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "2.19.0"
SHELL = "/bin/bash"
TERM = "xterm-256color"
XDG_SESSION_TYPE = "tty"
```

Start by reproducing `kiro-cli update` on the reported Linux environment and inspect the updater path that handles unpacking `kiro-cli-chat`. Compare the update failure with the successful `kiro-cli doctor` output and existing updater tests, if available. Done means an update from version 2.19.0 completes without the unpack error and the installed CLI reaches the new version.

Written by the indexing model from the issue text.