fix(security): patch critical security vulnerabilities

- Remove User::$guarded = [] to prevent mass assignment attacks
- Enable SQL strict mode and disable emulated prepares (SQL injection prevention)
- Switch password hashing from bcrypt to argon2id (stronger algorithm)
- Enable session encryption to protect session data at rest
- Restrict TrustProxies to localhost only (prevent IP spoofing)
- Restrict CORS allowed_methods via env variable instead of wildcard
- Add PayPal amount mismatch detection to prevent payment manipulation
- Add double-capture prevention (idempotency check)
- Add expected_amount column to transactions table for verification

config/cors.php

@@ -19,7 +19,7 @@ return [
 
     'paths' => ['api/*', 'sanctum/csrf-cookie'],
 
-    'allowed_methods' => ['*'],
+    'allowed_methods' => array_filter(array_map(trim(...), explode(',', (string) env('CORS_ALLOWED_METHODS', 'GET,POST,PUT,PATCH,DELETE,OPTIONS'))), fn ($v) => $v !== ''),
 
     'allowed_origins' => array_filter(array_map(trim(...), explode(',', (string) env('CORS_ALLOWED_ORIGINS', ''))), fn ($v) => $v !== ''),