Fix HTTPS_PROXY env var not honored when proxy is unset

[Copilot]

Explicitly passing proxy=None to aiohttp's ws_connect()/session.get() overrides trust_env=True on the session, preventing HTTPS_PROXY (and related env vars) from being picked up automatically.

Changes

• communicate.py: Build ws_kwargs dict conditionally; only include proxy key when self.proxy is not None, then unpack into session.ws_connect()
• voices.py: Same pattern for session.get() in __list_voices()

# Before — proxy=None explicitly suppresses trust_env behaviour
session.ws_connect(..., proxy=self.proxy, ...)

# After — omitting proxy when None lets aiohttp honour HTTPS_PROXY via trust_env
ws_kwargs: Dict[str, object] = {}
if self.proxy is not None:
    ws_kwargs["proxy"] = self.proxy
session.ws_connect(..., **ws_kwargs, ...)

No behaviour change when proxy is explicitly set by the caller.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>HTTPS_PROXY env support</issue_title>
<issue_description>### Issue
HTTPS_PROXY environment variable not honored
Explicitly specifying the proxy in a Connection may not always be practical (upstream projects, dockerized environments).

Problem

Currently, when self.proxy is None (default), it's still explicitly passed to ws_connect() as proxy=None. This prevents aiohttp from using the environment variables (HTTPS_PROXY) even though trust_env=True is set on the session.

Suggested Workaround

In Communicate, fallback to env HTTPS_PROXY if proxy is None</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes HTTPS_PROXY env support #455

---

📍 Connect Copilot coding agent with Jira, Azure Boards or Linear to delegate work to Copilot in one click without leaving your project management tool.

[rany2]

This doesn't even seem correct. trust_env is honored even if proxy is explicitly set to None.