Amazon Q self-signed certificate in certificate chain in VSCode

## Problem
When trying to chat in VSCode, the response shows as "self-signed certificate in certificate chain", while the inline completion feature works fine.

## Steps to reproduce the issue
We are having an enterprise network here with self-signed certs, but all the settings have been done in windows system, it's been fixed for other extension before, but now Amazon Q seems not to work with there settings. What we have done here includes:

1. Set VSCode `Http: Proxy Support` to `override`
2. Add system environment variables `NODE_EXTRA_CA_CERTS=path/to/certs` and `NODE_OPTIONS=--use-openssl-ca`
3. Tried VSCode settings `"http.experimental.systemCertificatesV2": true`

None of the above is working

## Expected behavior
Inline Completion and Chat should both work, or they should just won't work altogether.

## System details (run `AWS: About` and/or `Amazon Q: About`)

- OS: Windows 10
- Visual Studio Code version: 1.100.2
- AWS Toolkit version: Not installed
- Amazon Q version: 1.70.0

Start by reproducing the failure in VSCode Chat on Windows 10 with the listed proxy, NODE_EXTRA_CA_CERTS, NODE_OPTIONS, and system-certificate settings, then compare it with Inline Completion, which works. Done means both features consistently handle the enterprise self-signed certificate chain, or the supported limitation is documented.

Written by the indexing model from the issue text.