FileHasher: download ældre versioner

Adds a Subfolders control so folder scans can cover everything, the chosen folder alone, or a set number of levels, and remembers your algorithm and metadata choices between runs. The Browse dialogs now open at the path already in the box, and the window no longer opens taller than the screen at high display scaling.

Moves the app to .NET 10, the current long-term-support release, which also makes the download smaller. Fixes the window layout at display scaling above 100%, where buttons and labels could previously be clipped or overlap.

Adds an in-app help window (F1), a Verify Sidecars mode that re-checks files against their existing sidecar hash files, a results context menu (open Explorer/PowerShell/cmd at a file, copy hash or path), an extended sidecar format carrying modified date and size, and sidecar suggestions that follow the selected hash algorithm.

First release distributed via winget. Adds a signed MSI installer with Start Menu integration and clean upgrades between versions; hashing features unchanged from 0.2.x.