bug: Input method won't register on macOS 26 Tahoe (M5) - autocomplete never attaches

### 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 26.6.2 (25G83), Apple M5 Pro (arm64)

### Expected behaviour

Running kiro-cli integrations install input-method should register the Kiro autocomplete input method with macOS. It should appear under System Settings → Keyboard → Input Sources and autocomplete should work in supported terminals such as Ghostty.

### Actual behaviour

Running kiro-cli integrations install input-method gets stuck on the Keyboard Settings step.

The input method never appears under System Settings → Keyboard → Input Sources → + → English. Searching for whisperer also returns nothing.

Because the input method is never registered, autocomplete never attaches and no autocomplete overlay appears in Ghostty.

I also tried uninstalling and reinstalling Kiro CLI, reinstalling the input method, restarting macOS, relaunching the helper, and refreshing LaunchServices, with no effect.

kiro-cli doctor reports:

kiro-cli-term is not running in this terminal

The issue still exists on Kiro CLI 2.19.1.

### Steps to reproduce

1. Install Kiro CLI on macOS 26 Tahoe.
2. Run:
kiro-cli integrations install input-method
3. The installer opens Keyboard Settings but the input method never appears.
4. Go to System Settings → Keyboard → Input Sources → + → English.
5. CodeWhispererInputMethod is not listed, or any custom input source.
6. Restart Kiro CLI/macOS and open Ghostty.
7. Autocomplete still does not appear.

### Environment

```yaml
Kiro CLI: 2.19.1.
OS: macOS 26.6.2 (25G83)
Chip: Apple M5 Pro (arm64)
Terminal: Ghostty

kiro-cli doctor:
"kiro-cli-term is not running in this terminal"

Additional details:
- CodeWhispererInputMethod never appears in macOS Input Sources.
- AppleEnabledInputSources never lists codewhisperer.
- The input-method bundle signature is valid.
- Reinstalling Kiro CLI and the input method does not help.
- Restarting macOS does not help.
- Refreshing LaunchServices with lsregister does not help.
- Relaunching the input-method helper does not help.
```

Start by reproducing `kiro-cli integrations install input-method` on macOS 26.6.2 with the listed environment, then trace the input-method installation step that remains stuck. Done means the input method appears in macOS Input Sources and autocomplete attaches and displays in Ghostty.

Written by the indexing model from the issue text.