Make close button after action is completed not open confirmation

[TheLazySquid]

Summary

This PR makes the "Quit" button after installing not open the system prompt to confirm whether the user wants to quit installation. I believe that this prompt is unintentional, since it is unnecessary and makes the install process a bit clunkier. The quit button is disabled mid-action so there is no risk of the user accidentally quitting while the install is still happening.

Type of change

• Bug fix
• New feature / behavior change
• UI / component change (frontend)
• Backend / installer logic (Go)
• Build / release / CI
• Refactor (no behavior change)
• Documentation
• Other:

Testing

• bun run check passes (frontend, from frontend/)
• bun run lint passes (frontend, from frontend/)
• bun run test passes (frontend, from frontend/)
• go test ./... passes (backend)

AI disclosure

• I did not use AI assistance for this PR
• I used AI assistance and personally reviewed all generated output before submitting
• An AI agent generated part or all of this PR with minimal personal review. Details:

[zerebos]

It was intentional to have a quit prompt there rather than just exiting. But I will give this some thought.

[Zacam]

Pretty Please:

Instead of "Quit", can it just say Exit instead, and if the install progress is successful, not popup a confirmation Dialogue framed to ask if the user wants to "Cancel the Installation"?

Because the current behavior implies or can make people think that it's going to undo doing the install if they "Quit" on a successful install.