Add WeBuy license validation and usage logging API endpoints

- Add /api/license/webuy/ endpoint for license validation
- Add /api/license/webuy/log/ endpoint for usage logging
- Logs stored in /var/www/logs/webuy_usage.log

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

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

api/license/webuy/log/index.php

@@ -0,0 +1,26 @@
+<?php
+header('Content-Type: application/json');
+
+if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+    http_response_code(405);
+    exit;
+}
+
+$input = json_decode(file_get_contents('php://input'), true);
+if (!$input || empty($input['machineId']) || empty($input['timestamp'])) {
+    http_response_code(400);
+    exit;
+}
+
+$logEntry = sprintf(
+    "%s | %s | %s\n",
+    date('Y-m-d H:i:s'),
+    $input['machineId'],
+    $input['timestamp']
+);
+
+$logFile = __DIR__ . '/../../../../../logs/webuy_usage.log';
+file_put_contents($logFile, $logEntry, FILE_APPEND | LOCK_EX);
+
+http_response_code(200);
+echo '{"status":"ok"}';