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

app/models/license_store.php

@@ -0,0 +1,40 @@
+<?php
+// app/models/license_store.php
+require_once __DIR__ . '/../db.php';
+
+function license_upsert_from_verification(array $norm) {
+  // $norm: [
+  //   'key','source','plan','product_id','valid'=>bool,'expires_at'=>null|iso,'meta'=>array
+  // ]
+  $pdo = getPDO();
+
+  // 1) upsert into licenses
+  $stmt = $pdo->prepare("
+    INSERT INTO licenses
+      (license_key, source, plan, product_id, status, expires_at, meta_json, last_verified_at, created_at, updated_at)
+    VALUES
+      (:k, :src, :plan, :pid, :status, :exp, :meta, NOW(), NOW(), NOW())
+    ON DUPLICATE KEY UPDATE
+      source=:src, plan=:plan, product_id=:pid, status=:status,
+      expires_at=:exp, meta_json=:meta, last_verified_at=NOW(), updated_at=NOW()
+  ");
+  $stmt->execute([
+    ':k'     => $norm['key'],
+    ':src'   => $norm['source'],
+    ':plan'  => $norm['plan'],
+    ':pid'   => $norm['product_id'] ?? null,
+    ':status'=> $norm['valid'] ? 'active' : 'invalid',
+    ':exp'   => $norm['expires_at'] ?? null,
+    ':meta'  => json_encode($norm['meta'] ?? [], JSON_UNESCAPED_UNICODE),
+  ]);
+
+  // 2) Return row snapshot (minimal)
+  return [
+    'key'        => $norm['key'],
+    'source'     => $norm['source'],
+    'plan'       => $norm['plan'],
+    'status'     => $norm['valid'] ? 'active' : 'invalid',
+    'product_id' => $norm['product_id'] ?? null,
+    'expires_at' => $norm['expires_at'] ?? null,
+  ];
+}