[BUG] VS Code model picker lists Sonnet 4.6 twice (alias + pinned ID)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The model picker in the VS Code extension shows claude-sonnet-4-6 twice:

1. Sonnet — "Best for everyday tasks" (alias, resolves to current recommended Sonnet)
2. Sonnet 4.6 — "Best for everyday tasks (claude-sonnet-4-6)" (pinned model ID)

Both entries resolve to the same model. The distinction between alias and pinned version is not explained in the UI.

Expected behavior

Each model should appear once. If the alias/pinned distinction matters, show it as a single entry with a label (e.g. "always latest" vs pinned).

Environment

• Platform: macOS
• Claude Code VS Code extension