feat(commands): sort /help output alphabetically

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pkg/commands/cmd_help.go

@@ -3,6 +3,7 @@ package commands
 import (
 	"context"
 	"fmt"
+	"sort"
 	"strings"
 )
 
@@ -28,8 +29,12 @@ func formatHelpMessage(defs []Definition) string {
 		return "No commands available."
 	}
 
-	lines := make([]string, 0, len(defs))
-	for _, def := range defs {
+	sorted := make([]Definition, len(defs))
+	copy(sorted, defs)
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i].Name < sorted[j].Name })
+
+	lines := make([]string, 0, len(sorted))
+	for _, def := range sorted {
 		usage := def.EffectiveUsage()
 		if usage == "" {
 			usage = "/" + def.Name