Add --help and --version to plerdall and plerdwatcher

[iamllcoolray]

Summary

Adds --help and --version flags to both CLI scripts, using Getopt::Long's
parse-failure path and Pod::Usage for consistent, informative output instead
of the previous silent/confusing failure modes.

• --version prints <script> is part of Plerd $Plerd::VERSION and exits 0.
  lib/Plerd.pm already declares our $VERSION, so this just surfaces it.
• --help runs pod2usage(-verbose => 1), printing the script's SYNOPSIS
  and OPTIONS sections (already documented in POD) and exits 0.
• A failed option parse (e.g. an unrecognized flag) now runs
  pod2usage(-verbose => 0, -exitval => 2) instead of falling through to an
  unrelated "can't find config file" error.
• Both new options are handled immediately after GetOptions, before any
  config file resolution, so --help/--version work with no config
  present.
• Also fixes a pre-existing copy-paste bug in plerdwatcher's POD, where the
  --config example referenced bin/plerdall instead of bin/plerdwatcher.

Testing

Added t/cli_options.t, following the system() + Capture::Tiny pattern
used in t/init.t, covering both scripts:

• --version exits 0, output includes the version string, no stderr
• --help exits 0, output includes the program name and documents --config, no stderr
• an unrecognized option exits non-zero

Closes #47, #48