Adopts golangci-lint v2.12.2 and the canonical .golangci.yml (default: all), and fixes all resulting findings across the tree.
Two intended behavior changes: absent MFFilePath.Mtime is handled explicitly in freshen, list and export rather than dereferenced (main panicked); gpg positional key IDs now follow an explicit -- end-of-options marker.
All twelve reworded user-visible error messages restored to byte-identical parity with main and pinned by tests.
- Atomic writes for mfer gen: writes to temp file, renames on success,
cleans up temp on error/interrupt. Prevents empty manifests on Ctrl-C.
- Humanized byte sizes using dustin/go-humanize (e.g., "10 MiB" not "10485760")
- Progress lines clear when done (using ANSI escape \r\033[K])
- Debug logging when files are added to manifest (mfer gen -vv)
- Move -v/-q flags from global to per-command for better UX
- Add tests for atomic write behavior with failing filesystem mock
Replace callback-based progress reporting in Builder.AddFile with
channel-based FileHashProgress for consistency with EnumerateStatus
and ScanStatus patterns. Update scanner.go to use the new channel API.
