Label the version report's date line "commit date" (closes #409)

The value is the commit's date, which the Makefile and the Dockerfile
stamp in, not the time of the build. The other labels gain one space
so every value still starts in one column.

Model: opus-5-5

internal/cli/version.go

@@ -38,7 +38,7 @@ func writeVersion(out *ui.Writer) {
 
 	_, _ = fmt.Fprintf(w, "vaultik %s\n", globals.Version)
 	_, _ = fmt.Fprintf(w, "  commit:      %s\n", globals.Commit)
-	_, _ = fmt.Fprintf(w, "  build date: %s\n", globals.CommitDate)
+	_, _ = fmt.Fprintf(w, "  commit date: %s\n", globals.CommitDate)
 	_, _ = fmt.Fprintf(w, "  go:          %s\n", runtime.Version())
 	_, _ = fmt.Fprintf(w, "  os/arch:     %s/%s\n", runtime.GOOS, runtime.GOARCH)
 	_, _ = fmt.Fprintf(w, "  author:      %s\n", globals.Author)

internal/cli/version_test.go

@@ -49,6 +49,25 @@ func TestVersionCommandReportsBuildVersion(t *testing.T) {
 	}
 }
 
+// TestVersionCommandLabelsCommitDate checks that the date line is
+// labelled as the commit's date, which is what the build stamps into
+// it, and that its value starts in the same column as the commit's.
+//
+//nolint:paralleltest // executes a command that reads the global rootFlags
+func TestVersionCommandLabelsCommitDate(t *testing.T) {
+	out := runVersionCommand(t)
+
+	wantLine := "  commit date: " + globals.CommitDate
+	if !strings.Contains(out, wantLine+"\n") {
+		t.Errorf("output has no line %q:\n%s", wantLine, out)
+	}
+
+	wantCommit := "  commit:      " + globals.Commit
+	if !strings.Contains(out, wantCommit+"\n") {
+		t.Errorf("output has no line %q:\n%s", wantCommit, out)
+	}
+}
+
 // TestVersionCommandFlagsDevelopmentBuild is the regression test for
 // the thing this command exists to prevent: a build that is not a
 // release must say so. The notice used to be gated on the version