refactor: 精簡 /health 回應欄位

移除 php_version、laravel、environment、memory_mb，
保留 status、timestamp、checks 三欄。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

routes/web.php

@@ -27,10 +27,6 @@ Route::get('/health', function () {
     return response()->json([
         'status'    => $healthy ? 'ok' : 'degraded',
         'timestamp' => now()->toIso8601String(),
-        'environment' => app()->environment(),
-        'php_version' => PHP_VERSION,
-        'laravel'     => app()->version(),
-        'memory_mb'   => round(memory_get_usage(true) / 1024 / 1024, 2),
         'checks'    => $checks,
     ], $healthy ? 200 : 503);
 });