[FEATURE] Login to VSCode sidebar using API Key

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

As of Sep 29, Claude Code V2.0.0 was released, which aslo brought the new sidebar experience as part of the VSCode extension. Not everyone has access to an anthropic account, and just like https://github.com/anthropics/claude-code/issues/441, it would be great to sign in to the sidebar using just an API key.

Proposed Solution

The easiest way would be to honor existing keys present in ~/.claude/settings.json (apiKeyHelper or env.ANTHROPIC_API_KEY) or even honor the ANTHROPIC_API_KEY if present.

Alternative Solutions

Right now on a Mac I need to manually edit the password for Claude Code saved in my keychain. It's cumbersome but it works. It would be nice if existing env vars were honored.

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

This relates to the VSCode extension, I'm not sure if it uses a different platform to track feature requests.