Unable to run q chat behind corporate network which requires custom CA bundle.

### 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 14.7.1 (23H222)

### Expected behaviour

- Start terminal session
- Type q login -> select Pro License
- Q login with Pro License opens a browser where user authenticates Q Pro License
- Once logged in, type q chat enters q session
- Ask "Write a python hello world code". The Q should generate the code.

### Actual behaviour

Q chat with a prompt "Write a python hello world code" errors out with below

```
Amazon Q is having trouble responding right now:
0: dispatch failure (io error): an i/o error occurred: error sending request for url (https://codewhisperer.us-east-1.amazonaws.com/)
1: dispatch failure
2: io error
3: an i/o error occurred: error sending request for url (https://codewhisperer.us-east-1.amazonaws.com/)

Location:
/private/tmp/788abf33-519d-4264-918b-e563eeb425ff/crates/q_chat/src/lib.rs:1015

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.
```

### Steps to reproduce

- Start terminal session
- Type q login -> select Pro License
- Q login with Pro License opens a browser where user authenticates Q Pro License
- Start ZScaler
- Q Chat
- Ask "Write a python hello world code".
- The chat will error out.

We typically pass a custom CA bundler using AWS_CA_BUNDLE= for usual AWS CLI tasks while behind ZScaler.

### Environment

```yaml

[q-details]
version = "1.9.1"
hash = "5d2c2807cab9bc6c9dc5fcd05f92c7a979e8a4f7"
date = "2025-04-29T06:22:42.917989Z (9d ago)"
variant = "full"

[system-info]
os = "macOS 14.7.1 (23H222)"
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/zsh"
shell-version = "5.9"
terminal = "iTerm 2"
install-method = "brew"

[env-vars]
PATH = "/Users/USER/.nvm/versions/node/v20.5.1/bin:/usr/local/opt/node@16/bin:/Users/USER/.pyenv/shims:/Users/USER/.local/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:/usr/local/share/dotnet:~/.dotnet/tools:/Users/USER/.cargo/bin:/Applications/iTerm.app/Contents/Resources/utilities:/Users/USER/.local/bin"
QTERM_SESSION_ID = "d6e95b8b005e4601a3a1cb4bb5577dc1"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "1.9.1"
Q_USING_ZSH_AUTOSUGGESTIONS = "1"
SHELL = "/bin/zsh"
TERM = "xterm-256color"
__CFBundleIdentifier = "com.googlecode.iterm2"
```