fix(ns): class_exists() must use FQCN after PSR-4

Bare class_exists('Balance') looks up global Balance, always false
under AKSRT\* namespaces → REST 403 on balance exchange and friends.
Rewrite string checks to AKSRT\{Domain}\{Class}.

src/AKSRT/User/Badges.php

@@ -473,7 +473,7 @@ class Badges {
 				return (float) $counts;
 
 			case 'followed':
-				if (class_exists('Follow')) {
+				if (class_exists('AKSRT\\User\\Follow')) {
 					return (float) Follow::get_instance()->get_follower_count($user_id);
 				}
 				return 0.0;

src/AKSRT/User/BadgesAdmin.php

@@ -31,11 +31,11 @@ class BadgesAdmin {
 	}
 
 	private function can_manage(): bool {
-		return class_exists('Badges') && Badges::can_manually_set(get_current_user_id());
+		return class_exists('AKSRT\\User\\Badges') && Badges::can_manually_set(get_current_user_id());
 	}
 
 	public function render_section(\WP_User $user): void {
-		if (!class_exists('Badges') || !Badges::enabled()) {
+		if (!class_exists('AKSRT\\User\\Badges') || !Badges::enabled()) {
 			return;
 		}
 		$dict  = Badges::get_dictionary();
@@ -102,7 +102,7 @@ class BadgesAdmin {
 		if (!isset($_POST['aksrt_user_badges_nonce']) || !wp_verify_nonce(sanitize_text_field(wp_unslash((string) $_POST['aksrt_user_badges_nonce'])), 'aksrt_user_badges_admin')) {
 			return;
 		}
-		if (!class_exists('Badges') || !Badges::enabled()) {
+		if (!class_exists('AKSRT\\User\\Badges') || !Badges::enabled()) {
 			return;
 		}
 		$raw = isset($_POST['aksrt_user_badges']) ? (array) wp_unslash($_POST['aksrt_user_badges']) : [];

src/AKSRT/User/Home.php

@@ -161,7 +161,7 @@ class Home {
 
         if (!empty($settings['badge']['enabled']) && !empty($settings['badge']['public_display'])) {
             $limit = max(1, (int) ($settings['badge']['limit'] ?? 3));
-            if (class_exists('Badges')) {
+            if (class_exists('AKSRT\\User\\Badges')) {
                 $list = Badges::list_for_user($user_id, true);
                 $badge_count = 0;
                 foreach ((array) ($list['items'] ?? []) as $item) {
@@ -284,7 +284,7 @@ class Home {
         if ($source === 'manual_meta') {
             return max(0, (int) get_user_meta($user_id, 'aksrt_user_level', true));
         }
-        if (class_exists('Level')) {
+        if (class_exists('AKSRT\\User\\Level')) {
             return Level::get_level($user_id);
         }
         // Fallback: credits_balance thresholds (legacy) if integral class missing.

src/AKSRT/User/Metrics.php

@@ -73,7 +73,7 @@ class Metrics {
 	}
 
 	public static function reevaluate_medals(int $user_id): void {
-		if ($user_id > 0 && class_exists('Badges') && method_exists('Badges', 'auto_evaluate')) {
+		if ($user_id > 0 && class_exists('AKSRT\\User\\Badges') && method_exists('AKSRT\\User\\Badges', 'auto_evaluate')) {
 			Badges::auto_evaluate($user_id);
 		}
 	}
@@ -263,7 +263,7 @@ class Metrics {
 	/* ---------- level XP bridges ---------- */
 
 	private static function level_add(int $user_id, string $key): void {
-		if ($user_id > 0 && class_exists('Level')) {
+		if ($user_id > 0 && class_exists('AKSRT\\User\\Level')) {
 			Level::add($user_id, $key);
 		}
 	}