feat: enhance agent management and validation logic

- Updated AGENTS.md to clarify agent account restrictions and permissions.
- Implemented checks in AgentNodeAdminUserStoreController and AgentNodeRoleStoreController to restrict admin user and role creation to the agent's own node.
- Enhanced validation in AdminPlayerStoreController and AdminPlayerUpdateController to enforce credit limit and rebate rate rules based on player funding mode.
- Refactored various request classes to utilize shared admin account field rules for consistency.
- Improved error handling in services related to credit allocation and rebate limits to ensure proper validation and messaging.

tests/Unit/ApiValidationErrorsTest.php

@@ -17,6 +17,18 @@ test('normalizes business shorthand unique in zh', function (): void {
     expect($errors['code'][0])->toBe('该内容已存在，请更换后重试。');
 });
 
+test('normalizes rebate exceeds limit with field specific message in zh', function (): void {
+    $errors = ApiValidationErrors::normalize(['rebate_rate' => ['exceeds_limit']], 'zh');
+
+    expect($errors['rebate_rate'][0])->toBe('回水比例不能超过代理回水上限。');
+});
+
+test('normalizes settlement bill not payable in zh', function (): void {
+    $errors = ApiValidationErrors::normalize(['bill' => ['not_payable']], 'zh');
+
+    expect($errors['bill'][0])->toBe('当前账单状态不允许登记收付，请先确认账单。');
+});
+
 test('summary joins multiple field errors', function (): void {
     $normalized = [
         'code' => ['编码格式不正确。'],