Integrates post-download malware scanning using Windows Defender on Windows platforms. Adds scan status tracking, rescan and delete actions for infected files, and updates the downloads UI to display scan results and actions. Non-Windows platforms show scan as unavailable.
Implements a full downloads manager with Electron main process handling, IPC APIs, and renderer integration. Adds a dedicated downloads page, a mini downloads popup in the navigation bar with progress ring, and controls for pausing, resuming, canceling, opening, and showing downloads. Updates styles and navigation to support the new downloads features.
andrew