GPUI: Project heading terminal button does not start a terminal on Windows

[maddada]

Environment

• GPUI app
• Windows

Problem

A terminal cannot be started from the terminal button in a project's sidebar heading.

Steps to reproduce

1. Open the sidebar.
2. Click the terminal button in a project heading.
3. Observe that a terminal does not start.

Expected behavior

Clicking the project heading terminal button should start a terminal for that project.

[maddada]

Applied fix in the working tree.

• The project-heading terminal action now has an explicit native intent on local Windows instead of splitting creation between the CEF sidebar and native attachment.
• Rust reuses the canonical host-owned New Terminal flow: gxserver creates the durable session, supplies the authoritative WSL cwd/attach plan, and the exact project workspace slot is opened.
• Remote projects and macOS/Linux retain their existing creation paths.

Final static verifier: PASS.

Per request, no tests, builds, app launch, commit, or push were performed.