[Feature]: Allow hiding the Thread details panel by default for new threads#17251

Feature request

Please allow the Thread details panel to be hidden by default for new threads, with a persistent app-wide preference.

This is the panel containing the environment/workspace, Open in VS Code, Add project script, and Initialize Git controls. Its toolbar button is labeled Toggle thread details panel.

Current behavior

• A new thread opens with this panel visible.
• Hiding it is remembered for that individual thread.
• Opening a different new thread shows the panel again.
• I could not find a global default visibility preference in General or Appearance settings.

Requested behavior

Let users set Show Thread details by default to off, so every new thread starts with the panel hidden. Keep the existing toolbar toggle available to reveal it when needed.

Remembering the last chosen visibility as the default for new threads would also satisfy this request.

Why this helps

The panel takes up space and adds visual clutter when I only want to focus on the conversation. I rarely need these workspace controls, so repeatedly hiding the panel for each new thread is unnecessary friction.

How to reproduce the current behavior

1. Open a new thread, including a thread with No project selected.
2. Hide the panel using Toggle thread details panel.
3. Open a different new thread.
4. Observe that the panel is visible again.

Environment

• T3 Code desktop (Nightly)
• Version: 0.0.46-nightly.20261008.2813
• macOS, Apple Silicon