Consolidate CLI commands to reduce top-level surface area

- migrate-* commands → subcommands of `bd migrate`
- relate/unrelate → subcommands of `bd dep`
- daemons subcommands → available under `bd daemon`
- comment alias → hidden with deprecation warning

All old commands still work with deprecation warnings for backwards
compatibility. Reduces visible top-level commands from ~73 to 66.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/migrate_issues.go

@@ -14,8 +14,7 @@ import (
 
 // TODO: Consider integrating into 'bd doctor' migration detection
 var migrateIssuesCmd = &cobra.Command{
-	Use:     "migrate-issues",
-	GroupID: "maint",
+	Use:     "issues",
 	Short:   "Move issues between repositories",
 	Long: `Move issues from one source repository to another with filtering and dependency preservation.
 
@@ -692,7 +691,7 @@ func loadIDsFromFile(path string) ([]string, error) {
 }
 
 func init() {
-	rootCmd.AddCommand(migrateIssuesCmd)
+	migrateCmd.AddCommand(migrateIssuesCmd)
 
 	migrateIssuesCmd.Flags().String("from", "", "Source repository (required)")
 	migrateIssuesCmd.Flags().String("to", "", "Destination repository (required)")
@@ -710,4 +709,11 @@ func init() {
 
 	_ = migrateIssuesCmd.MarkFlagRequired("from") // Only fails if flag missing (caught in tests)
 	_ = migrateIssuesCmd.MarkFlagRequired("to")   // Only fails if flag missing (caught in tests)
+
+	// Backwards compatibility alias at root level (hidden)
+	migrateIssuesAliasCmd := *migrateIssuesCmd
+	migrateIssuesAliasCmd.Use = "migrate-issues"
+	migrateIssuesAliasCmd.Hidden = true
+	migrateIssuesAliasCmd.Deprecated = "use 'bd migrate issues' instead"
+	rootCmd.AddCommand(&migrateIssuesAliasCmd)
 }