[bug] First-run onboarding wizard (step 4/6): runtime options card overflows window height — bottom content clipped and unreadable

[Harsh9485]

Summary

During the first-run onboarding wizard, Step 4/6 displays a card listing all available runtime buttons. The card is taller than the visible window area. The bottom buttons — along with the Back / Next navigation buttons — are clipped outside the viewport and cannot be read. There is no scroll mechanism to reach them.

Additionally, window drag stops working while the onboarding wizard is open. The app cannot be moved until the wizard is dismissed.

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Steps to reproduce

1. Launch Mux for the first time (or reset config so the onboarding wizard appears).
2. Proceed through the wizard until Step 4/6.
3. Observe that the buttons (Local, Worktree, SSH, Coder SSH, Docker…) extend beyond the visible window area.
4. Attempt to scroll within the card — no scroll is available.
5. The bottom buttons and the Back / Next navigation buttons are clipped and unreadable.
6. Without closing the wizard, try to drag the app window by clicking and dragging the title bar — window drag does not work.

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Expected behavior

• All runtime buttons and the Back / Next navigation buttons should be fully visible at any window size. The modal should either constrain its height to the available viewport with a scroll, or adapt its layout so all content fits within the window without overflow.
• The window should remain draggable from the title bar while the onboarding wizard is open.

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Actual behavior

• The runtime buttons card has no scroll constraint. The card grows taller than the window, pushing the bottom buttons and the Back / Next navigation buttons out of view with no way to scroll to them.
• Window drag does not work while the onboarding wizard is open. The app cannot be moved until the wizard is closed.

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Environment

Field	Value
Mux version	v0.27.1
OS	Windows 11
Trigger	First-run onboarding, Step 4/6

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Screenshots

[linear-code]

MUX-47