polish the api route, response, health, cache, and metrics

public/index.php

@@ -0,0 +1,43 @@
+<?php
+// public/index.php — tiny router
+require __DIR__.'/../app/bootstrap.php';
+require __DIR__.'/../app/helpers/cors.php';
+require __DIR__.'/../app/helpers/logger.php';
+require __DIR__.'/../app/helpers/json.php';
+$reqId = log_start();
+
+// Log at shutdown with final status code
+register_shutdown_function(function() use ($reqId) {
+  $status = http_response_code();
+  if (function_exists('log_end')) log_end($reqId, $status ?: 200);
+});
+
+$path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH) ?: '/';
+
+// CORS preflight
+if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') { cors_preflight(); exit; }
+
+// Routes (v1)
+if ($path === '/v1/emojis')                      { require __DIR__.'/../app/controllers/Emojis.php'; exit; }
+if (preg_match('#^/v1/emoji/([^/]+)$#', $path, $m)) {
+  $_GET['slug'] = urldecode($m[1] ?? '');
+  require __DIR__.'/../app/controllers/Emojis.php';
+  exit;
+}
+if ($path === '/v1/license/activate')            { require __DIR__.'/../app/controllers/License.php'; exit; }
+if ($path === '/v1/license/verify')              { require __DIR__.'/../app/controllers/License.php'; exit; }
+if ($path === '/v1/license/deactivate')          { require __DIR__.'/../app/controllers/License.php'; exit; }
+
+// Health
+if ($path === '/v1/health') {
+  cors_allow();
+  header('Content-Type: application/json; charset=utf-8');
+  header('Vary: Origin,User-Agent');
+  echo json_encode(['ok'=>true,'time'=>gmdate('c')]);
+  exit;
+}
+
+if ($path === '/v1/metrics') { require __DIR__.'/../app/controllers/Metrics.php'; exit; }
+if ($path === '/v1/metrics-lite') { require __DIR__.'/../app/controllers/MetricsLite.php'; exit; }
+
+json_error(404, 'not_found', ['path' => $path]);