feat: Add --start flag to bd daemon, show help with no args

Currently 'bd daemon' with no args immediately starts the daemon. This is
inconsistent with other daemon management commands like --stop, --status,
etc. and makes the command less discoverable for new users.

Changes:
- Add --start flag to explicitly start daemon
- Show help text when no operation flags provided
- Update auto-start logic to use --start flag
- Update startDaemon() to pass --start when forking
- Update all documentation to use 'bd daemon --start'
- Update MCP Python client error messages

The MCP docs already incorrectly showed 'bd daemon start' which doesn't
work, so this change fixes that documentation bug while improving UX.

Auto-start still works correctly - it now passes --start internally.

Fixes bd-gfu

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

cmd/bd/daemon.go

@@ -21,8 +21,8 @@ import (
 
 var daemonCmd = &cobra.Command{
 	Use:   "daemon",
-	Short: "Run background sync daemon",
-	Long: `Run a background daemon that automatically syncs issues with git remote.
+	Short: "Manage background sync daemon",
+	Long: `Manage the background daemon that automatically syncs issues with git remote.
 
 The daemon will:
 - Poll for changes at configurable intervals (default: 5 seconds)
@@ -32,10 +32,15 @@ The daemon will:
 - Pull remote changes periodically
 - Auto-import when remote changes detected
 
-Use --stop to stop a running daemon.
-Use --status to check if daemon is running.
-Use --health to check daemon health and metrics.`,
+Common operations:
+  bd daemon --start          Start the daemon
+  bd daemon --stop           Stop a running daemon
+  bd daemon --status         Check if daemon is running
+  bd daemon --health         Check daemon health and metrics
+
+Run 'bd daemon' with no flags to see available options.`,
 	Run: func(cmd *cobra.Command, args []string) {
+		start, _ := cmd.Flags().GetBool("start")
 		stop, _ := cmd.Flags().GetBool("stop")
 		status, _ := cmd.Flags().GetBool("status")
 		health, _ := cmd.Flags().GetBool("health")
@@ -47,9 +52,15 @@ Use --health to check daemon health and metrics.`,
 		logFile, _ := cmd.Flags().GetString("log")
 		global, _ := cmd.Flags().GetBool("global")
 
+		// If no operation flags provided, show help
+		if !start && !stop && !status && !health && !metrics && !migrateToGlobal {
+			_ = cmd.Help()
+			return
+		}
+
 		// If auto-commit/auto-push flags weren't explicitly provided, read from config
 		// (skip if --stop, --status, --health, --metrics, or --migrate-to-global)
-		if !stop && !status && !health && !metrics && !migrateToGlobal && !global {
+		if start && !stop && !status && !health && !metrics && !migrateToGlobal && !global {
 			if !cmd.Flags().Changed("auto-commit") {
 				if dbPath := beads.FindDatabasePath(); dbPath != "" {
 					ctx := context.Background()
@@ -112,6 +123,14 @@ Use --health to check daemon health and metrics.`,
 			return
 		}
 
+		// If we get here and --start wasn't provided, something is wrong
+		// (should have been caught by help check above)
+		if !start {
+			fmt.Fprintf(os.Stderr, "Error: --start flag is required to start the daemon\n")
+			fmt.Fprintf(os.Stderr, "Run 'bd daemon --help' to see available options\n")
+			os.Exit(1)
+		}
+
 		// Skip daemon-running check if we're the forked child (BD_DAEMON_FOREGROUND=1)
 		// because the check happens in the parent process before forking
 		if os.Getenv("BD_DAEMON_FOREGROUND") != "1" {
@@ -197,6 +216,7 @@ Use --health to check daemon health and metrics.`,
 }
 
 func init() {
+	daemonCmd.Flags().Bool("start", false, "Start the daemon")
 	daemonCmd.Flags().Duration("interval", 5*time.Second, "Sync check interval")
 	daemonCmd.Flags().Bool("auto-commit", false, "Automatically commit changes")
 	daemonCmd.Flags().Bool("auto-push", false, "Automatically push commits")

cmd/bd/daemon_autostart.go

@@ -103,7 +103,7 @@ func restartDaemonForVersionMismatch() bool {
 		return false
 	}
 
-	args := []string{"daemon"}
+	args := []string{"daemon", "--start"}
 	cmd := exec.Command(exe, args...)
 	cmd.Env = append(os.Environ(), "BD_DAEMON_FOREGROUND=1")
 
@@ -267,7 +267,7 @@ func startDaemonProcess(socketPath string, isGlobal bool) bool {
 		binPath = os.Args[0]
 	}
 
-	args := []string{"daemon"}
+	args := []string{"daemon", "--start"}
 	if isGlobal {
 		args = append(args, "--global")
 	}

cmd/bd/daemon_lifecycle.go

@@ -387,7 +387,7 @@ func startDaemon(interval time.Duration, autoCommit, autoPush bool, logFile, pid
 		os.Exit(1)
 	}
 
-	args := []string{"daemon",
+	args := []string{"daemon", "--start",
 		"--interval", interval.String(),
 	}
 	if autoCommit {