Autocomplete Shows Stale and Duplicate ssh Hosts

### 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 15.7.2 (24G325)

### Expected behaviour

When invoking cli autocompletion for the `ssh` command, the list of available ssh hosts should be populated by available hosts from the `.ssh/config` file. The list of hosts should be unique and not stale.

### Actual behaviour

When invoking cli autocompletion for the `ssh` command, the list of available ssh hosts contains numerous duplicated entries and old entries that are no longer available in the `.ssh/config` file.

### Steps to reproduce

Type `ssh` in any terminal window which uses q/kiro-cli

### Environment

```yaml

[q-details]
version = "1.21.0"
hash = "dc54efd85f411d6b4347d192733ff40650d38dfb"
date = "2025-11-26T22:31:44.946762Z (9d ago)"
variant = "full"

[system-info]
os = "macOS 15.7.2 (24G325)"
chip = "Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz"
total-cores = 6
memory = "16.00 GB"

[environment]
cwd = "/Users/USER"
cli-path = "/Users/USER"
os = "Mac"
shell-path = "/bin/bash"
shell-version = "3.2.57"
terminal = "macOS"
install-method = "brew"

[env-vars]
QTERM_SESSION_ID = "e1efb1f885504994aa5a3d3bc6777963"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "1.21.0"
SHELL = "/bin/bash"
TERM = "xterm-256color"
__CFBundleIdentifier = "com.apple.Terminal"
```

Inizia dal punto di ingresso del completamento automatico della CLI per il comando `ssh` e riproduci il problema usando gli host di `.ssh/config`; nel report non viene indicato alcun file sorgente o test. Il lavoro è completato quando il completamento mostra ogni host attualmente configurato una sola volta e non include più gli host rimossi.

Scritto dal modello di indicizzazione a partire dal testo della issue.