feat: Implement basic build & push capabilities for services (#68)

* wip: Build experiments

* wip: overall structure for build/push

* ref: Split method, add test fixture

* feat: Basic push functionality

* ref: Better structure and output

* feat: Handle registry auth

* feat: Integrate with deploy

* ref: Split into files

* fix: Modernize push options

cmd/uncloud/main.go

@@ -75,6 +75,7 @@ func main() {
 
 	cmd.AddCommand(
 		NewDeployCommand(),
+		NewBuildCommand(),
 		caddy.NewRootCommand(),
 		cmdcontext.NewRootCommand(),
 		dns.NewRootCommand(),