fix(update): accept custom types from types.custom config (GH#hq-8hif1z)

The `bd update --type` command was rejecting custom types (like role, agent,
rig) even when configured via types.custom. The issue was that type validation
used IsValid() which only checks the 5 core types, ignoring custom types.

Changes:
- CLI (update.go): Use IsValidWithCustom() with types from config
- Storage (validators.go): Add validateIssueTypeWithCustom() function
- Storage (queries.go, transaction.go): Fetch and pass custom types

The error message now dynamically shows all valid types including custom ones.

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

internal/storage/sqlite/queries.go

@@ -886,11 +886,15 @@ func (s *SQLiteStorage) UpdateIssue(ctx context.Context, id string, updates map[
 		return fmt.Errorf("issue %s not found", id)
 	}
 
-	// Fetch custom statuses for validation
+	// Fetch custom statuses and types for validation (GH#hq-8hif1z)
 	customStatuses, err := s.GetCustomStatuses(ctx)
 	if err != nil {
 		return wrapDBError("get custom statuses", err)
 	}
+	customTypes, err := s.GetCustomTypes(ctx)
+	if err != nil {
+		return wrapDBError("get custom types", err)
+	}
 
 	// Build update query with validated field names
 	setClauses := []string{"updated_at = ?"}
@@ -902,8 +906,8 @@ func (s *SQLiteStorage) UpdateIssue(ctx context.Context, id string, updates map[
 			return fmt.Errorf("invalid field for update: %s", key)
 		}
 
-		// Validate field values (with custom status support)
-		if err := validateFieldUpdateWithCustomStatuses(key, value, customStatuses); err != nil {
+		// Validate field values (with custom status and type support)
+		if err := validateFieldUpdateWithCustom(key, value, customStatuses, customTypes); err != nil {
 			return wrapDBError("validate field update", err)
 		}