feat: add npm for js dependencies + move src/ files to root folder

- add node service in docker-compose.yml
- update .devcontainer Dockerfile by adding node, npm and vim
- init package.json for npm with tailwindcss, postcss, commitlint and commitizen as dev dependencies
- update default layout main header and footer
- replace CI's welcome_message.php with home.php listing all podcasts
- add AUTHORS.md file
- add docs folder in which to place castopod's technical documentation

app/Models/PodcastModel.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Models;
+
+use CodeIgniter\Model;
+
+class PodcastModel extends Model
+{
+    protected $table = 'podcasts';
+    protected $primaryKey = 'id';
+
+    protected $allowedFields = [
+        'title',
+        'name',
+        'description',
+        'episode_description_footer',
+        'image',
+        'language',
+        'category',
+        'explicit',
+        'author',
+        'owner_name',
+        'owner_email',
+        'type',
+        'copyright',
+        'block',
+        'complete',
+        'custom_html_head',
+    ];
+
+    protected $returnType = 'App\Entities\Podcast';
+    protected $useSoftDeletes = false;
+
+    protected $useTimestamps = true;
+}