Add confirmation dialog before deleting a project

[yandanp]

Description

Currently, deleting a project happens without a confirmation step. This can lead to accidental data loss.

Task

Add a confirmation dialog when the user clicks delete on a project. The dialog should:

• Show the project name
• Have "Cancel" and "Delete" buttons
• Focus on "Cancel" by default (safe default)

Tech

• Frontend (React/TypeScript)
• Can use @tauri-apps/plugin-dialog or a custom modal component
• Sidebar component: src/renderer/components/Sidebar.tsx

Getting Started

See CONTRIBUTING.md for setup instructions.