feat(public-ui): adapt public podcast and episode pages to wireframes

- adapt wireframes with responsive design
- refactor models methods to cache requests for faster queries
- update public controllers to cache pages while retaining analytics hits
- add platform links to podcast page
- add previous / next episodes in episode page
- update npm packages to latest versions

closes #30, #13

app/Models/UserModel.php

@@ -1,18 +1,33 @@
 <?php
 
+/**
+ * @copyright  2020 Podlibre
+ * @license    https://www.gnu.org/licenses/agpl-3.0.en.html AGPL3
+ * @link       https://castopod.org/
+ */
+
 namespace App\Models;
 
 class UserModel extends \Myth\Auth\Models\UserModel
 {
     protected $returnType = \App\Entities\User::class;
 
-    public function getPodcastContributors($podcast_id)
+    public function getPodcastContributors($podcastId)
     {
-        return $this->select('users.*, auth_groups.name as podcast_role')
-            ->join('users_podcasts', 'users_podcasts.user_id = users.id')
-            ->join('auth_groups', 'auth_groups.id = users_podcasts.group_id')
-            ->where('users_podcasts.podcast_id', $podcast_id)
-            ->findAll();
+        if (!($found = cache("podcast{$podcastId}_contributors"))) {
+            $found = $this->select('users.*, auth_groups.name as podcast_role')
+                ->join('users_podcasts', 'users_podcasts.user_id = users.id')
+                ->join(
+                    'auth_groups',
+                    'auth_groups.id = users_podcasts.group_id'
+                )
+                ->where('users_podcasts.podcast_id', $podcastId)
+                ->findAll();
+
+            cache()->save("podcast{$podcastId}_contributors", $found, DECADE);
+        }
+
+        return $found;
     }
 
     public function getPodcastContributor($user_id, $podcast_id)