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.
```

Beginne damit, `kiro-cli integrations install input-method` unter macOS 26.6.2 mit der aufgeführten Umgebung zu reproduzieren, und verfolge anschließend den Installationsschritt der Eingabemethode, der weiterhin hängen bleibt. Der Vorgang ist abgeschlossen, wenn die Eingabemethode in den macOS-Eingabequellen erscheint und die Autovervollständigung in Ghostty eingeblendet wird.

Vom Indexierungsmodell aus dem Issue-Text verfasst.