Support specifing sparseCheckout in flux bootstrap

Signed-off-by: piny940 <83708535+piny940@users.noreply.github.com>
Assisted-by: claude/opus-4.7

cmd/flux/bootstrap_git.go

@@ -311,6 +311,7 @@ func bootstrapGitCmdRun(cmd *cobra.Command, args []string) error {
 		TargetPath:        gitArgs.path.ToSlash(),
 		ManifestFile:      sync.MakeDefaultOptions().ManifestFile,
 		RecurseSubmodules: bootstrapArgs.recurseSubmodules,
+		SparseCheckout:    bootstrapArgs.sparseCheckout,
 	}
 	if gitProvider != "" {
 		syncOpts.Provider = gitProvider