show version with branch and commit in help and -version

- add -version flag (besides --version and -V)
- help output includes the version
- commit and branch are set via ldflags by goreleaser; plain go build
  falls back to the VCS revision embedded by Go

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.goreleaser.yaml

@@ -22,7 +22,7 @@ builds:
     flags:
       - -trimpath
     ldflags:
-      - -s -w -X main.version={{ .Version }}
+      - -s -w -X main.version={{ .Version }} -X main.commit={{ .ShortCommit }} -X main.branch={{ .Branch }}
     goos:
       - linux
       - darwin