Amazon Q CLI dispatch failure when connecting to CodeWhisperer endpoint

### 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

### Operating system

macOS 15.5.0 (24F74)

### Expected behaviour

Amazon Q CLI should successfully connect to the required endpoints and provide a response without connection errors.

### Actual behaviour

Amazon Q CLI is failing with a dispatch error when trying to connect to the CodeWhisperer endpoint (https://codewhisperer.us-east-1.amazonaws.com/). The error occurs during chat execution with the following message: "an unknown error occurred: error sending request for url (https://codewhisperer.us-east-1.amazonaws.com/)"

```
[chat-transcript]
Amazon Q is having trouble responding right now:
0: dispatch failure (other): an unknown error occurred: error sending request

> /issue

I'd be happy to help you report an issue or make a feature request. You can use the `report_issue` tool to submit your feedback directly. This will open a pre-filled GitHub issue template with details from our conversation.

Could you please provide:

1. A brief title for your issue or feature request
2. What behavior you're currently experiencing (for issues) or what feature you'd like to see added
3. Any specific steps to reproduce the issue (if applicable)
4. What you expected to happen instead (for issues) or how you envision the feature working

Once you provide these details, I can help you submit the report through the proper channels.
[Tool uses: none]

> Amazon Q dispatch failure Amazon Q is having trouble responding right now: >
0: dispatch failure (other): an unknown error occurred: error sending request for url (https://codewhisperer.us-east-1.amazonaws.com/)>
1: dispatch failure>
2: other>
3: an unknown error occurred: error sending request for url (https://codewhisperer.us-east-1.amazonaws.com/)>
>
Location:>
crates/chat-cli/src/cli/chat/mod.rs:1008>
>
BACKTRACE >
4 frames hidden >
5: chat_cli::cli::chat::ChatContext::try_chat::{{closure}}::h1abcd7fda3405768>
at :>
6: chat_cli::cli::chat::chat::{{closure}}::h01ba7686b69ef210>
at :>
7: chat_cli::cli::chat::launch_chat::{{closure}}::hb3716f62df43b754>
at :>
8: chat_cli::cli::Cli::execute::{{closure}}::hc37af26243cdcfd4>
at :>
9: tokio::runtime::park::CachedParkThread::block_on::heaa5502ca6301bbf>
at :>
10: tokio::runtime::context::runtime::enter_runtime::h347627c48c805f47>
at :>
11: tokio::runtime::runtime::Runtime::block_on::h1dfbc35387add72e>
at :>
12: chat_cli::main::hc38bbe3a1732e1a6>
at :>
13: std::sys::backtrace::__rust_begin_short_backtrace::h5982e7d6b7613cf1>
at :>
14: std::rt::lang_start::{{closure}}::h57e9afec184aee65>
at :>
15: std::rt::lang_start_internal::hacda2dedffd2edb4>
at :>
16: _main>
at :>
>
Run with COLORBT_SHOW_HIDDEN=1 environment variable to disable frame filtering.>
Run with RUST_BACKTRACE=full to include source snippets.

I'll help you report this issue with the Amazon Q CLI tool. Let me use the report_issue tool to submit a detailed bug report.
[Tool uses: report_issue]

(...truncated)
```

### Steps to reproduce

The error occurs when using the `q chat` CLI command. The backtrace shows the error happening in the chat execution flow, specifically in the ChatContext::try_chat method.

macOS 15.5 で `q chat` コマンドを使って失敗を再現し、`ChatContext::try_chat` と 1008 行目の周辺にある `crates/chat-cli/src/cli/chat/mod.rs` を調査します。リクエストを `https://codewhisperer.us-east-1.amazonaws.com/` まで追跡します。chat がエンドポイントに接続し、dispatch エラーなしでレスポンスを返せば完了です。

索引モデルが issue の本文から書いたものです。