Give -v to verbose, move --version to -V (closes #64)

urfave/cli's built-in version flag claimed -v, colliding with the -v
verbose alias on every subcommand, so "mfer -v --version" failed with a
parser error. Verbose is the more common meaning of -v in tools that
offer both, so verbose keeps -v at the root and on every subcommand, and
the version flag takes -V (--version still works).

User-visible change: -v alone now prints help with verbose logging, not
the version; use -V or --version.

The --version flag and the version subcommand share one printer, so
their output is identical. Tests cover -v, --verbose, --version, -V,
-v --version and --verbose --version. The README roadmap item for
--version is checked off.

Model: opus-4-8 (implementation); opus-5-5 (rebase)

TODO.md

@@ -24,6 +24,8 @@ only thing left of the `chore/align-repo-policies` branch is the list below.
 
 # Completed Steps
 
+- 2026-09-21: fixed the `-v` collision between `--verbose` and `--version`;
+  verbose owns `-v`, and version answers to `--version` and `-V` (#64)
 - 2026-10-03: pinned the CLI error messages by driving the functions that emit
   them in `internal/cli/errmsg_test.go`, and made the freshen mtime-presence
   test distinguish an absent mtime from the epoch (#87)