[Feature]: Replace native confirmation dialogs with T3-styled dialogs

[yiliangs]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case.

Area

apps/desktop

Problem or use case

Confirmation dialogs, such as Delete thread, use the native system appearance rather than T3 Code's visual language and theme. This makes them feel disconnected from the rest of the application.

Screenshot

Proposed solution

Use T3-styled in-app dialogs for confirmation flows while preserving expected modality, keyboard navigation, default and cancel actions, accessibility, and destructive-action emphasis.

Ideally, this should be implemented through the shared confirmation path so all confirmation-gated actions remain visually consistent.

Why this matters

Confirmation dialogs are a recurring part of the desktop experience. Styling them consistently would make the application feel more cohesive and intentional across platforms.

Version or commit

0.0.32

Environment

• OS: Windows 11
• App: T3 Code desktop

Related issue

#5167 concerns a Wayland crash in the native confirmation-dialog path. This request concerns replacing that native presentation with T3 Code's unified dialog styling.

[t3-code]

Closing as fixed by #5624: native confirmation prompts were replaced with themed dialogs.