Description
custard release vX.Y.Z hardcodes the annotated-tag message to the version string (internal/cli/verbs.go:166 — 'git tag -a -m '). Release() only reads args[0]; extra args like -m "msg" are silently ignored. Add a -m/--message flag so the release can carry a real message; fall back to the version when absent.
Acceptance Criteria
- #1 custard release vX.Y.Z -m "msg" sets the annotated tag message to msg
- #2 no -m given falls back to the version string (current behavior, unchanged)
- #3 unknown/extra args error instead of being silently ignored