HarborDrop 1.4.6

This maintenance release strengthens download completion integrity and browser handoff recovery.

Improvements

Tracks file-size provenance and remote resource identity before segmented downloads are merged.
Preserves browser handoff ownership across extension reloads and app restarts.
Uses typed engine outcomes for Direct, segmented, HLS, and yt-dlp completion validation.

Prevented partial responses and incomplete HLS playlists from being marked as completed downloads.
Prevented segmented merge when the remote resource changes during resume or retry.
Reconciles small browser downloads that finish during handoff without creating duplicate HarborDrop records.
Ensures browser pause and handoff claims terminate through import, resume, cancel, retry, or an explicit blocked state.
Added regression coverage for resource changes, incomplete output, extension reload recovery, and browser-completed import races.