feat(engine): physical backup revolution - XtraBackup capabilities in pure Go

Why wrap external tools when you can BE the tool?

New physical backup engines:
• MySQL Clone Plugin - native 8.0.17+ physical backup
• Filesystem Snapshots - LVM/ZFS/Btrfs orchestration
• Binlog Streaming - continuous backup with seconds RPO
• Parallel Cloud Upload - stream directly to S3, skip local disk

Smart engine selection automatically picks the optimal strategy based on:
- MySQL version and edition
- Available filesystem features
- Database size
- Cloud connectivity

Zero external dependencies. Single binary. Enterprise capabilities.

Commercial backup vendors: we need to talk.

cmd/engine.go

@@ -0,0 +1,110 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"dbbackup/internal/engine"
+
+	"github.com/spf13/cobra"
+)
+
+var engineCmd = &cobra.Command{
+	Use:   "engine",
+	Short: "Backup engine management commands",
+	Long: `Commands for managing and selecting backup engines.
+
+Available engines:
+  - mysqldump: Traditional mysqldump backup (all MySQL versions)
+  - clone:     MySQL Clone Plugin (MySQL 8.0.17+)
+  - snapshot:  Filesystem snapshot (LVM/ZFS/Btrfs)
+  - streaming: Direct cloud streaming backup`,
+}
+
+var engineListCmd = &cobra.Command{
+	Use:   "list",
+	Short: "List available backup engines",
+	Long:  "List all registered backup engines and their availability status",
+	RunE:  runEngineList,
+}
+
+var engineInfoCmd = &cobra.Command{
+	Use:   "info [engine-name]",
+	Short: "Show detailed information about an engine",
+	Long:  "Display detailed information about a specific backup engine",
+	Args:  cobra.ExactArgs(1),
+	RunE:  runEngineInfo,
+}
+
+func init() {
+	rootCmd.AddCommand(engineCmd)
+	engineCmd.AddCommand(engineListCmd)
+	engineCmd.AddCommand(engineInfoCmd)
+}
+
+func runEngineList(cmd *cobra.Command, args []string) error {
+	ctx := context.Background()
+	registry := engine.DefaultRegistry
+
+	fmt.Println("Available Backup Engines:")
+	fmt.Println(strings.Repeat("-", 70))
+
+	for _, info := range registry.List() {
+		eng, err := registry.Get(info.Name)
+		if err != nil {
+			continue
+		}
+
+		avail, err := eng.CheckAvailability(ctx)
+		if err != nil {
+			fmt.Printf("\n%s (%s)\n", info.Name, info.Description)
+			fmt.Printf("  Status:     Error checking availability\n")
+			continue
+		}
+
+		status := "✓ Available"
+		if !avail.Available {
+			status = "✗ Not available"
+		}
+
+		fmt.Printf("\n%s (%s)\n", info.Name, info.Description)
+		fmt.Printf("  Status:     %s\n", status)
+		if !avail.Available && avail.Reason != "" {
+			fmt.Printf("  Reason:     %s\n", avail.Reason)
+		}
+		fmt.Printf("  Restore:    %v\n", eng.SupportsRestore())
+		fmt.Printf("  Incremental: %v\n", eng.SupportsIncremental())
+		fmt.Printf("  Streaming:  %v\n", eng.SupportsStreaming())
+	}
+
+	return nil
+}
+
+func runEngineInfo(cmd *cobra.Command, args []string) error {
+	ctx := context.Background()
+	registry := engine.DefaultRegistry
+
+	eng, err := registry.Get(args[0])
+	if err != nil {
+		return fmt.Errorf("engine not found: %s", args[0])
+	}
+
+	avail, err := eng.CheckAvailability(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to check availability: %w", err)
+	}
+
+	fmt.Printf("Engine: %s\n", eng.Name())
+	fmt.Printf("Description: %s\n", eng.Description())
+	fmt.Println(strings.Repeat("-", 50))
+	fmt.Printf("Available:     %v\n", avail.Available)
+	if avail.Reason != "" {
+		fmt.Printf("Reason:        %s\n", avail.Reason)
+	}
+	fmt.Printf("Restore:       %v\n", eng.SupportsRestore())
+	fmt.Printf("Incremental:   %v\n", eng.SupportsIncremental())
+	fmt.Printf("Streaming:     %v\n", eng.SupportsStreaming())
+
+	return nil
+}