Add daemon fallback visibility and version compatibility checks

Implemented bd-150: Improve daemon fallback visibility and user feedback
- Added DaemonStatus struct to track connection state
- Enhanced BD_DEBUG logging with detailed diagnostics and timing
- Added BD_VERBOSE mode with actionable warnings when falling back
- Implemented health checks before using daemon
- Clear fallback reasons: connect_failed, health_failed, auto_start_disabled, auto_start_failed, flag_no_daemon
- Updated documentation

Implemented bd-151: Add version compatibility checks for daemon RPC protocol
- Added ClientVersion field to RPC Request struct
- Client sends version (0.9.10) in all requests
- Server validates version compatibility using semver:
  - Major version must match
  - Daemon >= client for backward compatibility
  - Clear error messages with directional hints (upgrade daemon vs upgrade client)
- Added ClientVersion and Compatible fields to HealthResponse
- Implemented 'bd version --daemon' command to check compatibility
- Fixed batch operations to propagate ClientVersion for proper checks
- Updated documentation with version compatibility section

Code review improvements:
- Propagate ClientVersion in batch sub-requests
- Directional error messages based on which side is older
- Made ServerVersion a var for future unification

Amp-Thread-ID: https://ampcode.com/threads/T-b5fe36b8-c065-44a9-a55b-582573671609
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/version.go

@@ -2,8 +2,11 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads"
+	"github.com/steveyegge/beads/internal/rpc"
 )
 
 const (
@@ -17,6 +20,13 @@ var versionCmd = &cobra.Command{
 	Use:   "version",
 	Short: "Print version information",
 	Run: func(cmd *cobra.Command, args []string) {
+		checkDaemon, _ := cmd.Flags().GetBool("daemon")
+		
+		if checkDaemon {
+			showDaemonVersion()
+			return
+		}
+		
 		if jsonOutput {
 			outputJSON(map[string]string{
 				"version": Version,
@@ -28,6 +38,55 @@ var versionCmd = &cobra.Command{
 	},
 }
 
+func showDaemonVersion() {
+	// Connect to daemon (PersistentPreRun skips version command)
+	// We need to find the database path first to get the socket path
+	if dbPath == "" {
+		// Use public API to find database (same logic as PersistentPreRun)
+		if foundDB := beads.FindDatabasePath(); foundDB != "" {
+			dbPath = foundDB
+		}
+	}
+	
+	socketPath := getSocketPath()
+	client, err := rpc.TryConnect(socketPath)
+	if err != nil || client == nil {
+		fmt.Fprintf(os.Stderr, "Error: daemon is not running\n")
+		fmt.Fprintf(os.Stderr, "Hint: start daemon with 'bd daemon'\n")
+		os.Exit(1)
+	}
+	defer client.Close()
+	
+	health, err := client.Health()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error checking daemon health: %v\n", err)
+		os.Exit(1)
+	}
+	
+	if jsonOutput {
+		outputJSON(map[string]interface{}{
+			"daemon_version":  health.Version,
+			"client_version":  Version,
+			"compatible":      health.Compatible,
+			"daemon_uptime":   health.Uptime,
+		})
+	} else {
+		fmt.Printf("Daemon version: %s\n", health.Version)
+		fmt.Printf("Client version: %s\n", Version)
+		if health.Compatible {
+			fmt.Printf("Compatibility: ✓ compatible\n")
+		} else {
+			fmt.Printf("Compatibility: ✗ incompatible (restart daemon recommended)\n")
+		}
+		fmt.Printf("Daemon uptime: %.1f seconds\n", health.Uptime)
+	}
+	
+	if !health.Compatible {
+		os.Exit(1)
+	}
+}
+
 func init() {
+	versionCmd.Flags().Bool("daemon", false, "Check daemon version and compatibility")
 	rootCmd.AddCommand(versionCmd)
 }