Unable to create Agents from CLI (both inside the Q Chat (ie. /agent create) or from the 'q' cli commands

### 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

Should be able to create Agents either from the CLI or from the Q Chat itself.

I'll note that the command _does_ seem to create the agent (the json file appears in the cli-agents folder) but just errors out in the terminal

Perhaps some remnant from the migration from profiles to agents? I do have a default agent set.. but I also tried with having it fall back to the in-memory configuration (I couldn't find a way to 'unset' the default agent

### Actual behaviour

```
q agent create --name "test1234" -vvv
..._Did not include all output from verbose command_...
2025-09-02T15:49:01.898558Z ERROR chat_cli::cli::agent: 869: Error loading global mcp json path: No such file or directory (os error 2).
error:
0: No such file or directory (os error 2)
```

```
[default] > /agent create --name "test1234"

Failed to execute command: No such file or directory (os error 2)
```

### Steps to reproduce

_No response_

### Environment

```yaml

[q-details]
version = "1.14.1"
hash = "209dfbf9c7bd73473a6712f3351158323f28e173"
date = "2025-08-21T18:25:42.366538Z (12d ago)"

[system-info]
os = "macOS 15.6.1 (24G90)"
chip = "Apple M1"
total-cores = 8
memory = "16.00 GB"

[environment]
cwd = "/Users/USER/dev/aws-samples/amazon-bedrock-agentcore-samples/02-use-cases/customer-support-assistant/prerequisite/policies"
cli-path = "/Users/USER/dev/aws-samples/amazon-bedrock-agentcore-samples/02-use-cases/customer-support-assistant/prerequisite/policies"
install-method = "unknown"

[env-vars]
PATH = "/Users/USER/.pyenv/shims:/Users/USER/.nvm/versions/node/v23.1.0/bin:/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/iTerm.app/Contents/Resources/utilities:/Users/USER/.local/bin:/Applications/Visual Studio Code.app/Contents/Resources/app/bin:/Users/USER/Library/Application Support/JetBrains/Toolbox/scripts:/Users/USER/.pyenv/bin:/Users/USER/Library/Python/3.9/bin:/Users/USER/bin:/Users/USER/.local/bin:/Users/USER/.toolbox/bin:/opt/homebrew/bin"
QTERM_SESSION_ID = "fb446835a32048ea8d6b6c4af052251d"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "1.14.1"
SHELL = "/bin/zsh"
TERM = "xterm-256color"
__CFBundleIdentifier = "com.googlecode.iterm2"
```