Reads the 4-byte magic of a file, looks it up in the shared
format table, and renames the file to use the correct .w*
extension. Useful when files have lost their extensions
(downloaded as 'data.bin', extracted from a tarball with
mangled metadata, or copied via a tool that strips suffixes).
Safe by default — refuses to overwrite an existing target;
pass --force to allow overwrite. --dry-run prints the planned
move without touching the filesystem. Files that already have
the correct extension are a no-op. Unrecognized magic exits
1 with the bytes printed for diagnostic context.
Reuses cli_format_table.cpp so any future format addition is
picked up automatically.
