JellyStat homepage: enable metadata popups end-to-end

- Add 'metadata' permission in jellystatHomepagePermissions
- Simplify and harden getJellyStatMetadata response path
- Ensure proper escaping in embedded JS and sanitize poster IDs
- Improve logging for route/method to aid debugging

Ready for remote testing via POST /api/v2/homepage/jellystat/metadata

api/homepage/jellystat.php

@@ -187,6 +187,17 @@ trait JellyStatHomepageItem
                     'homepageJellyStatAuth'
                 ],
                 'not_empty' => $requiredFields
+            ],
+            'metadata' => [
+                'enabled' => [
+                    'homepageJellyStatEnabled'
+                ],
+                'auth' => [
+                    'homepageJellyStatAuth'
+                ],
+                'not_empty' => [
+                    'jellyStatURL'
+                ]
             ]
         ];
         return $this->homepageCheckKeyPermissions($key, $permissions);