Initial implementation of mcdeploy deployment tool

Single Go binary with five commands:
- build: podman build locally with registry tags + git version
- push: podman push to MCR
- deploy: SSH pull/stop/rm/run on target node
- cert renew: issue TLS cert from Metacrypt via REST API
- status: show container status on a node

Config-driven via TOML service registry describing images,
Dockerfiles, container configs per node. Shells out to podman
for container operations and ssh for remote access.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

push.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+func pushCommand() *cobra.Command {
+	var imageFlag string
+
+	cmd := &cobra.Command{
+		Use:   "push <service>",
+		Short: "Push container images to the registry",
+		Args:  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			cfg, err := loadCfg()
+			if err != nil {
+				return err
+			}
+
+			svc, err := cfg.FindService(args[0])
+			if err != nil {
+				return err
+			}
+
+			images := svc.Images
+			if imageFlag != "" {
+				images = []string{imageFlag}
+			}
+
+			var pushed []string
+			for _, image := range images {
+				ref := cfg.ImageRef(image) + ":latest"
+				if err := run("podman", "push", ref); err != nil {
+					return fmt.Errorf("push %s: %w", image, err)
+				}
+				pushed = append(pushed, ref)
+			}
+
+			fmt.Printf("\nPushed %d image(s):\n", len(pushed))
+			for _, ref := range pushed {
+				fmt.Printf("  %s\n", ref)
+			}
+			return nil
+		},
+	}
+
+	cmd.Flags().StringVar(&imageFlag, "image", "", "push only this image")
+	return cmd
+}