1.0.3

refactor: rename autoupdate to selfupdate and polish CLI

- Rename autoupdate command/files to selfupdate throughout
- Add short-hand flags (-f, -j, -s, -i, -o, -m, -n) across
  all subcommands
- Fix semver comparison to use numeric sort instead of
  lexicographic
- Reject leading zeros in semver normalization
- Move Windows guard from downloadAndReplace into
  assetsForRuntime for earlier detection
- Make selfupdate reject extra args (cobra.NoArgs)
- Remove unused --force flag from template delete
- Reset appVersion to "dev" for development builds
- Expand test coverage for semver, checksum parsing,
  Windows rejection, and output formatters