feat(broker): add --version/-V so the self-update probe shows its version

[githubrobbi]

Problem

In uffs --update, every binary resolves a version except the broker:

- uffs-broker  ?

uffs-broker had no --version arm — any unrecognised flag falls through to the SCM service dispatch, which (run interactively) prints usage text. The self-update snapshot probes each binary with <bin> --version and parses a semver token from the output, so the broker came back as ?: the only binary without a resolvable version, leaving version-skew detection blind to it.

Fix

• Add a cross-platform --version / -V arm in main(), handled before the Windows-only service dispatch, printing uffs-broker <version> to stdout in the same shape as every other UFFS binary (uffs <version>). Works on every platform, exits 0.
• List --version in the usage help.
• Add a parse_version regression test for the hyphenated uffs-broker 0.6.9 line (the name's hyphen must not be mistaken for part of the version token).

Verification

$ uffs-broker --version   →  uffs-broker 0.6.9   (exit 0)
$ uffs-broker -V          →  uffs-broker 0.6.9   (exit 0)

Parser extracts 0.6.9; all 7 binaries::tests pass. Result: the uffs-broker ? line in uffs --update becomes uffs-broker 0.6.9.

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