bug: Can't add content to /knowledge

### 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 15.6.1 (24G90)

### Expected behaviour

When I enter something like:

/knowledge add "k8s-config-docs" /Users/bartvb/projects/k8s-infrastructure/docs
or
/knowledge add "k8s-config-docs" . --index-type Best
or
/knowledge add k8s-config --index-type Best /Users/bartvb/projects/k8s-infrastructure

I expect the tool to start scanning the folder and create a search index of that data.

### Actual behaviour

I always get:

`error: unexpected argument '/Users/bartvb/projects/k8s-infrastructure' found`

### Steps to reproduce

`/experiment` and enable 'knowledge'

Enter:

`/knowledge add "k8s-config-docs" /Users/bartvb/projects/k8s-infrastructure/docs`

### Environment

```yaml
[q-details]
version = "1.15.0"
hash = "eb8db5c635fc469f3bd94ead16bb4bfb32d7443b"
date = "2025-09-02T17:57:24.662205Z (14h ago)"
variant = "full"

[system-info]
os = "macOS 15.6.1 (24G90)"
chip = "Apple M2 Max"
total-cores = 12
memory = "64.00 GB"

[environment]
cwd = "/Users/USER/projects/k8s-infrastructure"
cli-path = "/Users/USER/projects/k8s-infrastructure"
os = "Mac"
shell-path = "/bin/zsh"
shell-version = "5.9"
terminal = "iTerm 2"
install-method = "brew"

[env-vars]
PATH = "/Users/USER/.local/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Applications/VMware Fusion.app/Contents/Public:/Applications/iTerm.app/Contents/Resources/utilities:/Users/USER/.krew/bin:/Applications/PhpStorm.app/Contents/MacOS:~.local/bin"
SHELL = "/bin/zsh"
TERM = "xterm-256color"
__CFBundleIdentifier = "com.googlecode.iterm2"
```